Multi-station grid-connected configuration method and system mixed with network-constructing converter

Abstract

The invention discloses a multi-station grid-connected configuration method and system mixed with a grid-forming inverter, and belongs to the technical field of power grid electric energy quality control. According to the configuration method, node mutual impedance is decoupled through capacity information of each region node, so that an equivalent power grid impedance model of each region is established, and the system is simplified to solve the problem of key region node stability. Secondly, describing a quantitative relation among equivalent power grid impedance, the capacity and the position of the network construction type converter and the stability margin of the system by using a D segmentation method, and accurately designing a configuration scheme of the network construction type converter under the requirement of determining the stability margin; according to the method, the curse of dimensionality of a multi-station system is broken through, a quantitative basis is provided for the minimum necessary capacity and the optimal position configuration of the network construction type converter under the constraint of the specific stability margin, and the stability of the new energy multi-station grid-connected system under the weak power grid condition is effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of power grid power quality control technology, and relates to the control technology and system configuration of new energy inverters. Specifically, it is a multi-site grid-connected configuration method and system that is mixed with grid-type converters. Background Technology

[0002] In recent years, the penetration rate of renewable energy sources such as wind power and photovoltaics in power systems has seen a leapfrog growth, and all-new energy power supply systems have entered the demonstration application stage. In such systems, grid-connected converters (GFLs) and grid-mounted converters (GFMs) constitute the core grid-connected units: GFLs synchronize the grid phase through phase-locked loops, possessing significant cost advantages; GFMs actively construct the grid frequency-type amplitude through virtual inertia control, providing critical stability support capabilities. Facing renewable energy systems with a percentage of power generation from multiple substations and long-distance transmission, how to scientifically determine the capacity ratio of GFMs and GFLs and their spatial distribution in the grid topology, while considering economic efficiency (reducing the proportion of high-cost GFMs), to maximize the system's small-signal stability, has become a pressing technical bottleneck that needs to be overcome.

[0003] Current research on the stability of converter hybrid systems mainly relies on two methods: modal analysis and impedance analysis. Modal analysis constructs a detailed state-space model and uses eigenvalue trajectories to assess system stability. By tracing the real parts of critical eigenvalues, it quantifies the upper limit of the stability boundary for GFM-type GFLs in new energy power generation systems. However, this method struggles to analyze the dynamic interaction mechanism of multiple converters and cannot quantify the system's stability margin, leading to significant differences in instability risks for systems with similar eigenvalue indices in practical engineering. Impedance analysis focuses on the coupling effect between controller parameters and grid impedance. Existing literature has established the equations of motion for the interaction of multiple GFM-type GFLs, revealing the regulation law of virtual inertia parameters on the system's synchronization capability. Currently, numerous academic papers and patents have studied multi-machine grid-connected new energy systems with hybrid grid configurations, such as:

[0004] 1. Chinese patent document CN118589473A, published on September 3, 2024, entitled "Optimal Ratio and Layout Design Method and Related Device for Grid-Type and Wire-Connected Converters in a 100% New Energy Multi-Machine System," proposes a method for optimizing the ratio and layout of GFM-type GFLs based on a distribution matrix. It searches for the optimal solution by establishing an analytical relationship between the distribution matrix and robust stability margin. However, its core relies on the accurate linearization of the small-signal model, which faces the curse of dimensionality in complex multi-station systems. More importantly, this method does not consider the impedance differences between nodes caused by long-distance power transmission; the same GFM deployed near and far from the grid will produce drastically different stability effects.

[0005] 2. Chinese patent document CN117937520B, published on March 20, 2024, entitled "A Stability Analysis Method and System for New Energy Multi-Machine Systems," proposes a quantitative method for the stability of new energy multi-machine systems based on amplitude-type frequency sensitivity. It calculates critical sensitivity indicators by real-time monitoring of electrical quantities at the grid connection point. While achieving quantitative evaluation of stability, its optimization object is limited to controller parameters and does not involve converter control types and spatial configurations, thus failing to solve the problem of optimal GFM (Gateway Controller) placement in multi-site systems.

[0006] In summary, existing technologies have two major shortcomings:

[0007] 1. Detailed state-space models and precise linearization relying on small-signal models face the curse of dimensionality in complex multi-site systems, potentially leading to discrepancies in stability criteria in practical engineering. While amplitude-based frequency sensitivity analysis can assess stability, it struggles to quantify system stability margins and fails to comprehensively consider economic objectives.

[0008] 2. Current methods only abstract "location" into a mathematical matrix, without establishing a mapping relationship between the geographical location of converters and the spatial distribution of grid impedance. In actual systems with multiple transmission lines, ignoring the differences in short-circuit capacity at station nodes will cause the GFM location scheme to deviate from the true optimal solution. Existing technologies lack a three-dimensional decision-making framework that simultaneously optimizes the capacity ratio, spatial location, and controller parameters of GFM-type GFLs under given cost constraints, making it difficult to achieve the global maximization of the system's robust stability margin. Summary of the Invention

[0009] To overcome the limitations of the aforementioned solutions, this invention proposes a multi-site grid-connected configuration method that combines grid-type converters with grid-connected systems. By decoupling the node mutual impedances through the capacity information of nodes in each region, an equivalent grid impedance model for each region is established, which can approximate and simplify the global system stability to the stability problem of key regional nodes. Secondly, the D-segmentation method is used to describe the quantitative relationship between equivalent grid impedance, grid-connected converter capacity and location, and system stability margin. This enables precise design of grid-connected converter configuration schemes under defined stability margin requirements, effectively improving the stability of multi-site grid-connected new energy systems under weak grid conditions.

[0010] The objective of this invention is achieved as follows: This invention provides a multi-station grid-connected configuration method that combines grid-type and grid-connected converters. The multi-station grid-connected system using this method includes a three-phase power grid and n renewable energy power stations. Each renewable energy power station consists of multiple grid-type and grid-connected converters, and the terminals of these multiple converters are connected in parallel to a single power station node. The n power station nodes of the n renewable energy power stations are connected to a common busbar through power station node branches, and the common busbar is connected to the three-phase power grid. The renewable energy power station is denoted as a power station, and any one of the n power station nodes is denoted as the i-th power station node, where i is the power station number, i = 1, 2, ..., n. The configuration method includes the following steps:

[0011] S1, define the following variables for the system: branch voltage column vector Branch current column vector Branch current source column vector Branch admittance matrix Y Bra Node voltage column vector With the correlation matrix A Def Based on circuit principles, the system of equations Π1 relating the variables is obtained.

[0012] S2, Solve the system of equations ∏1 to obtain the column vector of branch current sources. and node voltage column vector The relationship is given by ∏2, and the ratio of the two variables is defined as the network impedance matrix Z of the system's power transmission lines. Net_n ;

[0013] S3, Introduce the power generation normalization coefficient vector K I_x The equivalent grid impedance Z of the i-th power station node is obtained by utilizing the proportional relationship of power generation at each power station. gep_i ;

[0014] S4, calculate the equivalent control impedance Z inside the i-th station. oeq_k Equivalent collector line Z inside the station geq_k ;

[0015] S5, based on the equivalent circuit of the i-th station node, list the equivalent open-loop transfer function G. open An improved D-segmentation method is introduced, using the grid configuration capacity, configuration location, and equivalent grid impedance as key parameters to obtain the parameter stability boundary.

[0016] S6, introduces the phase-gain margin tester G test For the configuration parameters of the grid-type converter, a phase angle-gain margin tester is added as a composite constraint condition; the D-segment boundary is drawn to obtain the grid-type capacity configuration value and location configuration value under specific stability margin requirements.

[0017] Preferably, the branch voltage column vector S1 Branch current column vector Branch current source column vector Branch admittance matrix Y Bra Node voltage column vector With the correlation matrix A Def The expression is as follows:

[0018]

[0019] Y Bra =diag([Y1 … Y) i … Y n ])

[0020]

[0021] In the formula, U i Let I be the branch voltage of the i-th station node. i Let I be the branch current of the i-th station node. si Y is the current source of the i-th station node branch. i For the admittance of the i-th station node branch, U si Let a be the voltage of the i-th power station node. ij Let be the association value between the i-th station node and the j-th station node branch, where j is the station number, j = 1, 2, ..., n, and j ≠ i;

[0022] The expression for the system of equations ∏1 is as follows:

[0023]

[0024] Preferably, the relation H2 in S2 is as follows:

[0025]

[0026] The network impedance matrix Z Net_n The expression is as follows:

[0027]

[0028] In the formula, Z i，i Let be the self-impedance of the transmission line at the i-th station node.

[0029] Preferably, the power generation normalization coefficient vector K in S3 I_x The expression is as follows:

[0030] K I_x =[k i，1 … k i，j-1 k i，j k i，j+1 … ki，n ] T

[0031] Where, k i，j For the j-th station node current source I sj and the current source I of the i-th station node si The ratio, i.e., I sj =k i，j I si ;

[0032] The equivalent grid impedance Z of the i-th power station node gep_i The expression is as follows:

[0033]

[0034] Among them, Z ij Let be the transmission line impedance between the i-th power station node and the j-th power station node.

[0035] Preferably, the implementation process of S4 is as follows:

[0036] Let there be n stations in the i-th station. p There are n converters, and the impedance from the terminal of each converter to the station node is defined as the collector impedance, i.e., there are a total of n converters. p The largest of the several collector impedances is denoted as the maximum collector impedance Z. Teq_k ;

[0037] The equivalent control impedance Z inside the station oeq_k Equivalent collector impedance Z inside the station geq_k The expressions are as follows:

[0038] Z oeq_k =Z o_GFL / n p

[0039] Z geq_k =Z Teq_k / n p

[0040] Among them, Z o_GFL To control the output impedance in a grid-like manner.

[0041] Preferably, the equivalent open-loop transfer function G described in S5 open The expression is as follows:

[0042]

[0043] In the formula, Z o_GFM To control the output impedance in a grid-like manner, γ GFM The formula for configuring the ratio for grid-type converters is as follows:

[0044]

[0045] In the formula, S GFL S represents the total capacity of the grid-connected converters within the station. GFM This refers to the total capacity of the grid-type converters within the station;

[0046] Introducing the improved D-segmentation method, specifically, let K be the function parameter domain, and k be any value within the function parameter domain. Then, the parameter stability boundary of the D-segmentation method consists of the following equation:

[0047]

[0048] In the formula, D(±j im ω,k) is the transfer function equation, where j im Let j be the imaginary unit, satisfying j im 2 = -1, ω is the system angular frequency; a0(k) is the transfer function constant term, a n (k) is the nth term of the transfer function, δ0 is the singular boundary A, and δ n For singular boundary B, δ ω The boundary is a non-singular boundary. All three boundaries are curves and enclose a closed region, which is the parameter stability region.

[0049] Preferably, the phase angle-gain margin tester G described in S6 test The expression is as follows:

[0050]

[0051] In the formula, A GM For the gain margin, θ PM Set as phase margin;

[0052] The equivalent circuit open-loop transfer function G for each new energy power station open Adding a phase-gain margin tester as a composite constraint, we obtain equation Π3, as follows:

[0053] G open =G test

[0054] The equivalent circuits inside and outside the i-th station node are combined with the phase angle-gain margin tester G. test After substituting into equation ∏3, equation ∏3 transforms into the following form:

[0055]

[0056] Using the grid configuration capacity, configuration location parameters, and equivalent grid impedance as key parameters, the D-segmentation boundary is drawn to represent the quantitative relationship between the parameters, thus obtaining the grid configuration capacity and location configuration values ​​that meet specific stability margin requirements.

[0057] The present invention also provides a multi-site grid-connected configuration system that is mixed with grid-type converters, including a microprocessor and a memory, wherein the microprocessor is programmed or configured to execute the steps of the multi-site grid-connected configuration method that is mixed with grid-type converters.

[0058] The present invention also provides a computer-readable storage medium storing a computer program programmed or configured to perform the multi-site grid-connected configuration method of the grid-connected converter.

[0059] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0060] 1. This invention provides a multi-station grid-connected configuration method that integrates grid-type converters with grid-type configurations. By extracting the capacity characteristics of key regional nodes and decoupling mutual impedances, the global stability problem of complex multi-station systems is reduced in dimensionality and transformed into a local equivalent grid impedance stability determination. Compared with traditional full-model modal analysis and impedance modeling, this method overcomes the curse of dimensionality in multi-station systems and achieves efficient global stability assessment.

[0061] 2. In view of the shortcomings of existing technologies that cannot quantify the relationship between the location-based capacity of grid-connected converters and the system stability margin, this invention applies the D-segmentation method to construct a quantitative relationship between equivalent grid impedance, GFM installation location, GFM capacity ratio and system stability margin, providing a basis for the minimum necessary capacity and optimal location configuration of GFM under given stability margin constraints. Attached Figure Description

[0062] Figure 1 This is a topology diagram of a new energy multi-site grid-connected system applying the configuration method of the present invention in an embodiment of the present invention.

[0063] Figure 2 This is a flowchart of the configuration method of the present invention.

[0064] Figure 3 A quantitative relationship diagram for configuring the capacity of a grid-type converter under specific phase margin conditions.

[0065] Figure 4 A quantitative relationship diagram for the configuration location of a grid-type converter under specific phase margin conditions.

[0066] Figure 5 Analysis of PCC voltage waveform and THD for fully grid-controlled inverters under weak grid conditions.

[0067] Figure 6 Analysis of PCC voltage waveform and THD for a hybrid grid-type converter with a weak grid configuration. Detailed Implementation

[0068] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0069] This invention provides a multi-station grid-connected configuration method that combines grid-type and grid-connected converters. The multi-station grid-connected system using this method includes a three-phase power grid and n renewable energy power stations. Each renewable energy power station consists of multiple grid-type and grid-connected converters, with the terminals of these converters connected in parallel to a single power station node. The power station nodes of the n renewable energy power stations are connected to a common busbar via branch lines, and the common busbar is connected to the three-phase power grid. The renewable energy power stations are denoted as "stations," and any one of the n power station nodes is designated as the i-th power station node, where i is the station number, i = 1, 2, ..., n.

[0070] from Figure 1 Looking at the data above, n=5, meaning there are a total of 5 renewable energy power stations. These 5 power stations are connected to the three-phase power grid via radial or trunk transmission structures. The system's energy transmission path follows a clear direction: the DC source input is converted by a grid-connected converter, and the final grid-connected converter is connected in parallel to the power station node. The three-phase current flows from the power station node into the branches, and each branch is connected to the three-phase power grid via the transmission line impedance.

[0071] Figure 2 This is a flowchart illustrating the multi-site grid-connected configuration method of the present invention, which combines grid-type converters with grid-type configurations. Figure 2 As can be seen, the configuration method includes the following steps:

[0072] Step 1, define the following variables for the system: branch voltage column vector Branch current column vector Branch current source column vector Branch admittance matrix Y Bra Node voltage column vector With the correlation matrix A Def Based on circuit principles, the system of equations relating the variables is obtained as ∏1.

[0073] In this embodiment, the branch voltage column vector Branch current column vector Branch current source column vector Branch admittance matrix Y Bra Node voltage column vector With the correlation matrix A Def The expression is as follows:

[0074]

[0075] Y Bra =diag([Y1 … Y) i … Y n ])

[0076]

[0077] In the formula, U i Let I be the branch voltage of the i-th station node. i Let I be the branch current of the i-th station node. si Y is the current source of the i-th station node branch. i For the admittance of the i-th station node branch, U si Let a be the voltage of the i-th power station node. ij Let be the association value between the i-th station node and the j-th station node branch, where j is the station number, j = 1, 2, ..., n, and j ≠ i;

[0078] The expression for the system of equations ∏1 is as follows:

[0079]

[0080] Step 2: Solve the system of equations ∏1 to obtain the column vector of branch current sources. and node voltage column vector The relationship is given by ∏2, and the ratio of the two variables is defined as the network impedance matrix Z of the system's power transmission lines. Net_n .

[0081] In this embodiment, the relation ∏2 is as follows:

[0082]

[0083] The network impedance matrix Z Net_n The expression is as follows:

[0084]

[0085] In the formula, Z i，i Let be the self-impedance of the transmission line at the i-th station node.

[0086] Step 3, introduce the power generation normalization coefficient vector K I_x The equivalent grid impedance Z of the i-th power station node is obtained by utilizing the proportional relationship of power generation at each power station. gep_i .

[0087] In this embodiment, the power generation normalization coefficient vector K I_x The expression is as follows:

[0088] K I_x =[k i，1… k i，j-1 k i，j k i，j+1 … k i，n ] T

[0089] Where, k i，j For the j-th station node current source I sj and the current source I of the i-th station node si The ratio, i.e., I sj =k i，j I si .

[0090] The equivalent grid impedance Z of the i-th power station node gep_i The expression is as follows:

[0091]

[0092] Among them, Z ij Let be the transmission line impedance between the i-th power station node and the j-th power station node.

[0093] Step 4: Calculate the equivalent control impedance Z inside the i-th station. oeq_k Equivalent collector line Z inside the station geq_k .

[0094] In this embodiment, step 4 is implemented as follows:

[0095] Let there be n stations in the i-th station. p There are n converters, and the impedance from the terminal of each converter to the station node is defined as the collector impedance, i.e., there are a total of n converters. p The largest of the several collector impedances is denoted as the maximum collector impedance Z. Teq_k .

[0096] The equivalent control impedance Z inside the station oeq_k Equivalent collector impedance Z inside the station geq_k The expressions are as follows:

[0097] Z oeq_k =Z o_GFL / n p

[0098] Z geq_k =Z Teq_k / n p

[0099] Among them, Z o_GFL To control the output impedance Z of the mesh o_GFL .

[0100] Step 5: Based on the equivalent circuit of the i-th station node, list the equivalent open-loop transfer function G.open An improved D-segmentation method is introduced, using the grid configuration capacity, configuration location, and equivalent grid impedance as key parameters to obtain the parameter stability boundary.

[0101] In this embodiment, the equivalent open-loop transfer function G open The expression is as follows:

[0102]

[0103] In the formula, Z o_GFM To control the output impedance in a grid-like manner, γ GFM The formula for configuring the ratio for grid-type converters is as follows:

[0104]

[0105] In the formula, S GFL S represents the total capacity of the grid-connected converters within the station. GFM This refers to the total capacity of the grid-type converters within the power station.

[0106] Introducing the improved D-segmentation method, specifically, let K be the function parameter domain, and k be any value within the function parameter domain. Then, the parameter stability boundary of the D-segmentation method consists of the following equation:

[0107]

[0108] In the formula, D(±j im ω,k) is the transfer function equation, where j im Let j be the imaginary unit, satisfying j im 2 = -1, ω is the system angular frequency; a0(k) is the transfer function constant term, a n (k) is the nth term of the transfer function, δ0 is the singular boundary A, and δ n For singular boundary B, δ ω The boundary is a non-singular boundary. All three boundaries are curves and enclose a closed region, which is the parameter stability region.

[0109] Step 6, introduce the phase-gain margin tester G. test For the configuration parameters of the grid-type converter, a phase angle-gain margin tester is added as a composite constraint condition; the D-segment boundary is drawn to obtain the grid-type capacity configuration value and location configuration value under specific stability margin requirements.

[0110] In this embodiment, the phase angle-gain margin tester G test The expression is as follows:

[0111]

[0112] In the formula, AGM For the gain margin, θ PM Set as phase margin;

[0113] The equivalent circuit open-loop transfer function G for each new energy power station open Adding a phase-gain margin tester as a composite constraint, we obtain equation Π3, as follows:

[0114] G open =G test

[0115] The equivalent circuits inside and outside the i-th station node are combined with the phase angle-gain margin tester G. test After substituting into equation π3, equation π3 transforms into the following form:

[0116]

[0117] Using the grid configuration capacity, configuration location parameters, and equivalent grid impedance as key parameters, the D-segmentation boundary is drawn to represent the quantitative relationship between the parameters, thus obtaining the grid configuration capacity and location configuration values ​​that meet specific stability margin requirements.

[0118] The present invention also provides a multi-site grid-connected configuration system that is mixed with grid-type converters, including a microprocessor and a memory, wherein the microprocessor is programmed or configured to execute the steps of the multi-site grid-connected configuration method that is mixed with grid-type converters.

[0119] The present invention also provides a computer-readable storage medium storing a computer program programmed or configured to perform the multi-site grid-connected configuration method of the grid-connected converter.

[0120] The quantitative relationship of the configuration capacity of grid-type converters under specific phase margin conditions is as follows: Figure 3 As shown in the figure, when the grid-connected converter has a capacity of 0, the phase margin of the grid-connected system decreases to approximately -5° as the equivalent grid impedance Zgepi increases. The region below the critical curve at PM = 0° is unstable; this critical curve reflects the equivalent grid impedance Zgepi at critical stability. gep_i The quantitative relationship between Z and the configured capacity of grid-type converters. The slope of the curve reflects the positive correlation between the two. When configuring grid-type control strategy equipment, when Z... geq For every 0.2 pu increase, the grid-type energy storage required to maintain critical system stability needs to be increased by 1%.

[0121] The quantization relationship of the grid converter configuration location under specific phase margin conditions is as follows: Figure 4As shown, different curves represent the quantitative relationship between the location and capacity of the GFM control equipment under specific stability margin conditions. It can be seen that the farther the location of the grid-type control equipment is from the terminal node of the grid-type converter, the larger the unstable region, and the greater the capacity of the grid-type control equipment required for the hybrid configuration system to reach critical stability. When the location distance of the grid-type control equipment is 0.05 pu, the capacity required for the hybrid configuration system to reach critical stability is 5%. However, when the location distance is 0.15 pu, the capacity required for the hybrid configuration system to reach critical stability is 10%, requiring an additional 5% of the grid-type control equipment capacity under unchanged grid conditions.

[0122] To demonstrate the beneficial effects of the present invention, a simulation was performed.

[0123] Figure 5 This is the PCC voltage waveform and amplification when the grid-connected inverter is controlled in a weak grid environment. At this time, the equivalent grid impedance of each station node is less than the critical stability value, and the grid is under weak grid conditions, resulting in significant distortion of the PCC voltage waveform.

[0124] The multi-site grid-connected configuration method provided by this invention, which combines grid-type converters with grid-type converters, configures the grid-type converters at each node according to the quantified relationship between the configuration capacity and location of the grid-type converters. Figure 6 The waveform and amplification of the PCC voltage when the system is mixed with the grid-type converter under weak grid conditions are shown. At this time, the PCC voltage resonance is significantly suppressed and the grid-connected voltage of the system is restored to stability.

Claims

1. A method for configuring multi-station grid connection using a hybrid grid-type converter and a grid-connected converter, wherein the multi-station grid connection system using this method includes a three-phase power grid and n renewable energy power stations; each renewable energy power station consists of multiple grid-type converters and grid-connected converters, and the terminals of the multiple converters are connected in parallel to a power station node; the n power station nodes of the n renewable energy power stations are respectively connected to a common bus through power station node branches, and the common bus is connected to the three-phase power grid; the renewable energy power station is denoted as a power station, and any one of the n power station nodes is denoted as the i-th power station node, where i is the power station number, i = 1, 2, ..., n; characterized in that, The configuration method includes the following steps: S1, define the following variables for the system: branch voltage column vector Branch current column vector Branch current source column vector Branch admittance matrix Y Bra Node voltage column vector With the correlation matrix A Def Based on circuit principles, the system of equations relating the variables is obtained as ∏1; S2, Solve the system of equations ∏1 to obtain the column vector of branch current sources. and node voltage column vector The relationship is given by ∏2, and the ratio of the two variables is defined as the network impedance matrix Z of the system's power transmission lines. Net_n ; S3, Introduce the power generation normalization coefficient vector K I_x The equivalent grid impedance Z of the i-th power station node is obtained by utilizing the proportional relationship of power generation at each power station. gep_i ; S4, calculate the equivalent control impedance Z inside the i-th station. oeq_k Equivalent collector line Z inside the station geq_k ; S5, based on the equivalent circuit of the i-th station node, list the equivalent open-loop transfer function G. open An improved D-segmentation method is introduced, using the grid configuration capacity, configuration location, and equivalent grid impedance as key parameters to obtain the parameter stability boundary. S6, introduces the phase-gain margin tester G test For the configuration parameters of the grid-type converter, a phase angle-gain margin tester is added as a composite constraint condition; the D-segment boundary is drawn to obtain the grid-type capacity configuration value and location configuration value under specific stability margin requirements.

2. The multi-station grid-connected configuration method according to claim 1, which combines grid-type converters with grid-type configurations, is characterized in that... S1 Branch voltage column vector Branch current column vector Branch current source column vector Branch admittance matrix Y Bra Node voltage column vector With the correlation matrix A Def The expression is as follows: AND Bra =diag([Y1 … Y i … AND n ]) In the formula, U i Let I be the branch voltage of the i-th station node. i Let I be the branch current of the i-th station node. si Y is the current source of the i-th station node branch. i For the admittance of the i-th station node branch, U si Let a be the voltage of the i-th power station node. ij Let be the association value between the i-th station node and the j-th station node branch, where j is the station number, j = 1, 2, ..., n, and j ≠ i; The expression for the system of equations ∏1 is as follows:

3. The multi-station grid-connected configuration method according to claim 2, which combines grid-type converters with grid-type configurations, is characterized in that... The relation Π2 described in S2 is as follows: The network impedance matrix Z Net_n The expression is as follows: In the formula, Z i，i Let be the self-impedance of the transmission line at the i-th station node.

4. The multi-station grid-connected configuration method according to claim 3, which combines grid-type converters with grid-type configurations, is characterized in that... S3 refers to the power generation normalization coefficient vector K i_x The expression is as follows: K I_x =[k i，1 … k j-1 k i，j k i，j+1 … k i，n ] T Where, k i，j For the j-th station node current source I sj and the current source I of the i-th station node si The ratio, i.e., I sj =k i， j I si ; The equivalent grid impedance Z of the i-th power station node gep_i The expression is as follows: Among them, Z ij Let be the transmission line impedance between the i-th power station node and the j-th power station node.

5. The multi-station grid-connected configuration method according to claim 4, which combines grid-type converters with grid-type configurations, is characterized in that... The implementation process of S4 is as follows: Let there be n stations in the i-th station. p There are n converters, and the impedance from the terminal of each converter to the station node is defined as the collector impedance, i.e., there are a total of n converters. p The largest of the several collector impedances is denoted as the maximum collector impedance Z. Teq_k ; The equivalent control impedance Z inside the station oeq_k Equivalent collector impedance Z inside the station geq_k The expressions are as follows: WITH oeq_k =Z o_GFL / n p WITH geq_k =Z Teq_k / n p Among them, Z o_GFL To control the output impedance in a grid-like manner.

6. The multi-station grid-connected configuration method according to claim 5, which combines grid-type converters with grid-type configurations, is characterized in that... The equivalent open-loop transfer function G described in S5 open The expression is as follows: In the formula, Z o_GFM To control the output impedance of the grid, Y GFM The formula for configuring the ratio for grid-type converters is as follows: In the formula, S GFL S represents the total capacity of the grid-connected converters within the station. GFM This refers to the total capacity of the grid-type converters within the station; Introducing the improved D-segmentation method, specifically, let K be the function parameter domain, and k be any value within the function parameter domain. Then, the parameter stability boundary of the D-segmentation method consists of the following equation: In the formula, D(±j im ω,k) is the transfer function equation, where j im Let j be the imaginary unit, satisfying j im 2 = -1, ω is the system angular frequency; a0(k) is the transfer function constant term, a n (k) is the nth term of the transfer function, δ0 is the singular boundary A, and δ n For singular boundary B, δ ω The boundary is a non-singular boundary. All three boundaries are curves and enclose a closed region, which is the parameter stability region.

7. The multi-station grid-connected configuration method according to claim 6, which combines grid-type converters with grid-type configurations, is characterized in that... The phase-gain margin tester G described in S6 test The expression is as follows: In the formula, A GM For the gain margin, θ PM Set as phase margin; The equivalent circuit open-loop transfer function G for each new energy power station open Adding a phase-gain margin tester as a composite constraint, we obtain equation ∏3, as follows: G open =G test The equivalent circuits inside and outside the i-th station node are combined with the phase angle-gain margin tester G. test After substituting into equation π3, equation π3 transforms into the following form: Using the grid configuration capacity, configuration location parameters, and equivalent grid impedance as key parameters, the D-segmentation boundary is drawn to represent the quantitative relationship between the parameters, thus obtaining the grid configuration capacity and location configuration values ​​that meet specific stability margin requirements.

8. A multi-site grid-connected configuration system that integrates grid-type converters with grid-type configurations, characterized in that, It includes a microprocessor and a memory, the microprocessor being programmed or configured to perform the steps of the multi-site grid-connected configuration method according to any one of claims 1 to 7, which combines grid-type converters with grid-type configurations.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that is programmed or configured to perform the multi-site grid-connected configuration method of any one of claims 1 to 8, which is a combination of grid-type converters and grid-type configurations.

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