New energy base oscillation risk multi-port screening method, system and related device

Abstract

A new energy base oscillation risk multi-port screening method, system and related device, the method comprising: collecting basic data of a new energy base, the basic data of the new energy base comprising an impedance data set of a new energy unit, a grid structure and parameters of a new energy grid-connected system, and an operation mode of the new energy grid-connected system; obtaining a multi-port equivalent model of the new energy base by using the basic data of the new energy base through vector fitting, impedance aggregation and a multi-port model generation process; the oscillation risk of the multi-port equivalent model of the new energy base is evaluated by using a Nyquist stability criterion, and the oscillation risk at each port is quantitatively screened by using a damping ratio index. The improved stability judgment method considering the right half plane pole is provided based on the Nyquist stability criterion, the influence of the right half plane pole of the open-loop transfer function on stability judgment can be avoided, and accurate positioning of the oscillation dominant field station can be achieved by adopting the damping ratio index.

Description

Technical Field

[0001] This invention belongs to the field of new energy power generation technology, specifically relating to a multi-port screening method, system and related device for oscillation risk in new energy bases. Background Technology

[0002] Constructing large-scale new energy bases in desert, Gobi, and arid regions, and transmitting power over long distances via ultra-high-voltage AC / DC transmission channels, is a crucial approach to the development and utilization of new energy. These bases are located far from the main grid, have relatively weak local support capabilities, and contain diverse power plants, including wind power, photovoltaic power, thermal power, series compensation power, and DC power. These plants dynamically interact and couple with each other, posing a risk of broadband oscillations. Currently, oscillation risk screening and assessment are mainly conducted at the individual unit and substation levels. However, oscillation risk screening for large-scale grid-connected new energy systems involves numerous new energy units in different locations and with varying models, making it challenging and requiring further research.

[0003] The Shagohuang New Energy Base typically comprises several or even dozens of new energy power plants. The generating units within these plants are boosted and connected to the grid at the plant's connection point. These plants are interconnected via the main AC grid, and, in conjunction with traditional power generation from thermal and hydropower plants within the region, electricity is transmitted to load centers via ultra-high-voltage AC / DC transmission channels. For the Shagohuang New Energy Base power grid, since its grid structure is usually fixed—meaning the impedance characteristics of network components such as AC lines and transformers remain essentially constant—the factors determining system stability and oscillation risk are primarily the impedance characteristics of diverse devices under complex operating conditions. Operating modes mainly include unit output, line power flow, and electrical quantities such as the amplitude and phase angle of node voltages. Currently, in engineering practice, the main approach is to install broadband measurement devices at the new energy power plants to monitor voltage and current oscillation components online, and then suppress oscillations afterward using impedance analysis and reshaping techniques. However, this method lacks effective measures for pre-assessing potential oscillation risks at the system level. Summary of the Invention

[0004] The purpose of this invention is to address the problems in the prior art by providing a multi-port screening method, system, and related device for oscillation risks in new energy bases. This method pre-assesses potential oscillation risks at the system level, enabling quantitative assessment of broadband oscillation risks in large-scale new energy grid-connected systems and screening of oscillation-dominant stations.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] Firstly, a multi-portal screening method for oscillation risk in new energy bases is provided, including:

[0007] Collect basic data of new energy bases, including impedance data of new energy units, grid structure and parameters of new energy grid-connected systems, and operation mode of new energy grid-connected systems.

[0008] By utilizing the basic data of the new energy base, a multi-port equivalent model of the new energy base is obtained through vector fitting, impedance aggregation, and multi-port model generation processes.

[0009] The Nyquist stability criterion was used to assess the oscillation risk of the multi-port equivalent model of the new energy base, and the damping ratio index was used to quantitatively screen the oscillation risk at each port.

[0010] As a preferred embodiment, the impedance dataset of the new energy generating units includes impedance data of each new energy generating unit in the new energy grid-connected system under different operating modes;

[0011] The grid structure and parameters of a new energy grid-connected system include the system's wiring method and the parameters of transmission lines and transformers;

[0012] The operation mode of a new energy grid-connected system includes the output level of each power generation device and transmission device within the system.

[0013] As a preferred embodiment, in the step of obtaining a multi-port equivalent model of the new energy base through vector fitting, impedance aggregation, and multi-port model generation using basic data from the new energy base, the vector fitting process includes:

[0014] Establish an impedance model for new energy power generation devices;

[0015] The transfer function of the new energy power generation device is fitted using a vector fitting method.

[0016] The transfer function of the new energy power generation device is divided into frequency bands, and a corresponding fitting order is set for each frequency band. The control links that have less impact on impedance characteristics than the standard are ignored, and only the control links that play a dominant role in the impedance characteristics are retained. The impedance model of the new energy power generation device is simplified by frequency band division, so as to realize the frequency band order reduction fitting of the measured impedance of the new energy power generation device.

[0017] As a preferred embodiment, in the step of obtaining a multi-port equivalent model of the new energy base through vector fitting, impedance aggregation, and multi-port model generation using basic data from the new energy base, the impedance aggregation process includes:

[0018] Select a new energy power station and aggregate the portion of the selected new energy power station other than its grid connection port into a single grid-side impedance;

[0019] For the selected new energy power station, there exists a frequency of f. pPositive sequence disturbance voltage Frequency f n negative sequence disturbance voltage The following node voltage equations exist:

[0020]

[0021] In the formula, N is the number of nodes in the network-side system, and the positive-sequence node admittance matrix is ​​Y. Np The negative-order node admittance matrix is ​​Y. Nn 0 represents the zero vector; This represents the node voltage at the disturbance frequency. This represents the node voltage at the coupling frequency; This represents the current response generated by the negative-sequence disturbance voltage. This represents the negative-sequence current response generated by the positive-sequence perturbation voltage at the coupling frequency. The corresponding current generates a negative sequence disturbance voltage through the electrical network; y 0p This represents the positive-sequence connection admittance between the selected renewable energy power plant and the grid-side system, y 0p Indicates negative-order connectivity admittance;

[0022] The current response at the selected renewable energy power station is calculated using the following formula:

[0023]

[0024] In the formula, To select the positive sequence current of the node response of the new energy power station. To select the negative sequence current of the node response of the new energy power station, Σy 0p This represents the positive-sequence connection admittance y between the selected renewable energy power plant and the grid-side system. 0p Summing all elements in a vector;

[0025] The expressions for solving the positive-sequence and positive-sequence coupling impedances after aggregation of the network-side system are as follows:

[0026]

[0027] The expression for solving negative-order polymerization impedance is as follows:

[0028]

[0029] The pooled impedance of the grid-side system is represented by a 2×2 impedance matrix as follows:

[0030]

[0031] As a preferred embodiment, in the step of obtaining a multi-port equivalent model of the new energy base through vector fitting, impedance aggregation, and multi-port model generation using basic data from the new energy base, the multi-port model generation process includes: analyzing the grid connection ports of different new energy power stations within the new energy grid-connected system to obtain a port impedance dataset, and representing the new energy power station equivalently as a 2×2 station-side impedance Y. sys1 The system outside the grid connection port is aggregated into a 2×2 equivalent grid-side impedance matrix Y. sys2 This results in a multi-port system;

[0032] After considering the grid-side coupling impedance, the voltage and current relationship of the selected renewable energy power station conforms to the following expression:

[0033]

[0034] The voltage and current relationship of the selected renewable energy power station is represented as a dual-input dual-output (DIDO) feedback system. By judging the stability of the DIDO feedback system, the stability of the renewable energy grid-connected system under the corresponding operating mode is obtained.

[0035] As a preferred embodiment, the steps for assessing oscillation risk using the Nyquist stability criterion on the multi-port equivalent model of the new energy base include:

[0036] According to the expression of the Nyquist trajectory l(s):

[0037]

[0038] Let N be the number of times the trajectory of l(s) circles the point (-1,0) clockwise; N is positive when it circles clockwise and negative when it circles counterclockwise.

[0039] Solve for the pole distribution of the open-loop transfer function. The expression for the open-loop transfer function is: By solving for det[G(s)]=0, the number of poles in the right half-plane of the open-loop transfer function matrix is ​​obtained and denoted as P;

[0040] The expression for assessing oscillation risk is:

[0041] Z = N + P

[0042] Taking into account the influence of the number of poles in the right half-plane on the number of times the Nyquist curve wraps, the new energy grid-connected system is stable when Z = 0, and unstable when Z ≠ 0.

[0043] As a preferred embodiment, the step of using the damping ratio index to quantitatively screen the oscillation risk at each port includes: quantifying the stability margin at each port using the damping ratio, and solving for a mode s at each port using the following formula. k :

[0044] s k =-σ k +jω k k = 1, 2, 3, ..., N

[0045] In the formula, N represents the number of system modes; σk is the mode attenuation factor, ω k The frequency corresponding to the mode;

[0046] The damping ratio of a mode is calculated using the following formula:

[0047]

[0048] Where, when ξ i When <0, it indicates that the oscillation mode at the corresponding port is unstable and there is a risk of oscillation.

[0049] When ξ i A value greater than 0 indicates that there is no risk of oscillation at the corresponding port.

[0050] Secondly, a multi-port screening system for oscillation risk in new energy bases is provided, including:

[0051] The basic data collection module is used to collect basic data of the new energy base. The basic data of the new energy base includes the impedance data set of the new energy units, the grid structure and parameters of the new energy grid connection system, and the operation mode of the new energy grid connection system.

[0052] The multi-port equivalent model building module is used to obtain the multi-port equivalent model of the new energy base by using the basic data of the new energy base through vector fitting, impedance aggregation and multi-port model generation process.

[0053] The oscillation risk assessment and screening module is used to assess the oscillation risk of the multi-port equivalent model of the new energy base using the Nyquist stability criterion, and to quantitatively screen the oscillation risk at each port using the damping ratio index.

[0054] As a preferred embodiment, when the basic data collection module collects basic data of the new energy base, the impedance dataset of the new energy units includes the impedance data of each new energy unit in the new energy grid-connected system under different operating modes;

[0055] The grid structure and parameters of a new energy grid-connected system include the system's wiring method and the parameters of transmission lines and transformers;

[0056] The operation mode of a new energy grid-connected system includes the output level of each power generation device and transmission device within the system.

[0057] As a preferred embodiment, the multi-port equivalent model building module is executed during the vector fitting process:

[0058] Establish an impedance model for new energy power generation devices;

[0059] The transfer function of the new energy power generation device is fitted using a vector fitting method.

[0060] The transfer function of the new energy power generation device is divided into frequency bands, and a corresponding fitting order is set for each frequency band. The control links that have less impact on impedance characteristics than the standard are ignored, and only the control links that play a dominant role in the impedance characteristics are retained. The impedance model of the new energy power generation device is simplified by frequency band division, so as to realize the frequency band order reduction fitting of the measured impedance of the new energy power generation device.

[0061] As a preferred embodiment, the multi-port equivalent model building module is executed during the impedance aggregation process:

[0062] Select a new energy power station and aggregate the portion of the selected new energy power station other than its grid connection port into a single grid-side impedance;

[0063] For the selected new energy power station, there exists a frequency of f. p Positive sequence disturbance voltage Frequency f n negative sequence disturbance voltage The following node voltage equations exist:

[0064]

[0065] In the formula, N is the number of nodes in the network-side system, and the positive-sequence node admittance matrix is ​​Y. Np The negative-order node admittance matrix is ​​Y. Nn 0 represents the zero vector; This represents the node voltage at the disturbance frequency. This represents the node voltage at the coupling frequency; This represents the current response generated by the negative-sequence disturbance voltage. This represents the negative-sequence current response generated by the positive-sequence perturbation voltage at the coupling frequency. The corresponding current generates a negative sequence disturbance voltage through the electrical network; y 0p This represents the positive-sequence connection admittance between the selected renewable energy power plant and the grid-side system, y 0p Indicates negative-order connectivity admittance;

[0066] The current response at the selected renewable energy power station is calculated using the following formula:

[0067]

[0068] In the formula, To select the positive sequence current of the node response of the new energy power station. To select the negative sequence current of the node response of the new energy power station, Σy 0p This represents the positive-sequence connection admittance y between the selected renewable energy power plant and the grid-side system. 0p Summing all elements in a vector;

[0069] The expressions for solving the positive-sequence and positive-sequence coupling impedances after aggregation of the network-side system are as follows:

[0070]

[0071] The expression for solving negative-order polymerization impedance is as follows:

[0072]

[0073] The pooled impedance of the grid-side system is represented by a 2×2 impedance matrix as follows:

[0074]

[0075] As a preferred embodiment, the multi-port equivalent model building module is executed during the multi-port model generation process:

[0076] By analyzing the grid connection ports of different renewable energy power plants within the renewable energy grid-connected system, a port impedance dataset is obtained, and the renewable energy power plant is equivalently represented as a 2×2 power plant-side impedance Y. sys1 The system outside the grid connection port is aggregated into a 2×2 equivalent grid-side impedance matrix Y. sys2 This results in a multi-port system;

[0077] After considering the grid-side coupling impedance, the voltage and current relationship of the selected renewable energy power station conforms to the following expression:

[0078]

[0079] The voltage and current relationship of the selected renewable energy power station is represented as a dual-input dual-output (DIDO) feedback system. By judging the stability of the DIDO feedback system, the stability of the renewable energy grid-connected system under the corresponding operating mode is obtained.

[0080] As a preferred embodiment, when the oscillation risk assessment and screening module uses the Nyquist stability criterion to assess the oscillation risk of the multi-port equivalent model of the new energy base, it follows the expression of the Nyquist trajectory l(s):

[0081]

[0082] Let N be the number of times the trajectory of l(s) circles the point (-1,0) clockwise; N is positive when it circles clockwise and negative when it circles counterclockwise.

[0083] Solve for the pole distribution of the open-loop transfer function. The expression for the open-loop transfer function is: By solving for det[G(s)]=0, the number of poles in the right half-plane of the open-loop transfer function matrix is ​​obtained and denoted as P;

[0084] The expression for assessing oscillation risk is:

[0085] Z = N + P

[0086] Taking into account the influence of the number of poles in the right half-plane on the number of times the Nyquist curve wraps, the new energy grid-connected system is stable when Z = 0, and unstable when Z ≠ 0.

[0087] As a preferred embodiment, when the oscillation risk assessment and screening module uses the damping ratio index to quantitatively screen the oscillation risk at each port, it uses the damping ratio to quantify the stability margin at each port, and solves for a mode s at each port using the following formula. k :

[0088] s k =-σ k +jω k k = 1, 2, 3, ..., N

[0089] In the formula, N represents the number of system modes; σk is the mode attenuation factor, ω k The frequency corresponding to the mode;

[0090] The damping ratio of a mode is calculated using the following formula:

[0091]

[0092] Where, when ξ i When <0, it indicates that the oscillation mode at the corresponding port is unstable and there is a risk of oscillation.

[0093] When ξ i A value greater than 0 indicates that there is no risk of oscillation at the corresponding port.

[0094] Thirdly, an electronic device is provided, including a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the aforementioned multi-port screening method for oscillation risks in new energy bases.

[0095] Fourthly, a computer-readable storage medium is provided, the computer-readable storage medium storing at least one instruction, which, when executed by a processor, implements the multi-port screening method for oscillation risks in new energy bases.

[0096] Compared with the prior art, the first aspect of the present invention has at least the following beneficial effects:

[0097] By collecting basic data from renewable energy bases, a fundamental database is established for the renewable energy grid-connected system to be analyzed. This database serves as the basis for the analysis, primarily describing the equipment, lines, and operating modes of the renewable energy bases. A multi-port equivalent model of the renewable energy base is generated based on this data, mainly including vector fitting, impedance aggregation, and multi-port model generation. The renewable energy grid-connected system comprises n renewable energy power plants interconnected by a power network. When analyzing oscillations, ports can be divided at the grid connection points of each renewable energy power plant for analysis, obtaining a port impedance dataset. Each renewable energy power plant is then equivalent to a power plant-side impedance, and the system outside the grid connection ports is aggregated into an equivalent grid-side impedance matrix, thus forming a multi-port system. Subsequently, the Nyquist stability criterion is used to assess the oscillation risk. Due to the large-scale grid-connected renewable energy systems, the impedances of renewable energy power plants, DC transmission lines, synchronous machines, reactive power compensation devices, and transmission lines outside the grid connection ports are aggregated to obtain the grid-side active admittance. When the grid-side system is unstable, the loop gain of the renewable energy base feedback system will contain one or more right-half-plane poles, leading to open-loop system instability. According to the Nyquist criterion, judging the stability of the system also requires considering the number of right-half-plane poles in the open-loop transfer function. An unstable system may exhibit a Nyquist trajectory that does not circle the (-1,0) point, but still has right-half-plane poles. In this case, stability and stability margin cannot be judged solely by the trajectory. This invention proposes an improved stability judgment method that considers right-half-plane poles based on the Nyquist stability criterion, thereby avoiding the influence of right-half-plane poles in the open-loop transfer function on stability judgment. Furthermore, this invention uses the damping ratio index to quantitatively screen the oscillation risk at each port. For a multi-port system, the conclusions of stability analysis at different ports are consistent, but the specific stability margins obtained are different. Utilizing this characteristic, accurate location of the oscillation-dominant power plant can be achieved.

[0098] It is understood that the beneficial effects of the second to fourth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0099] To more clearly illustrate the technical solutions in the embodiments of this application, 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0100] Figure 1 A schematic diagram illustrating the design principle of the multi-port screening method for oscillation risk in new energy bases according to an embodiment of the present invention;

[0101] Figure 2 Schematic diagram of a multi-port access system for new energy power stations according to an embodiment of the present invention;

[0102] Figure 3 In this embodiment of the invention, the multi-port model generation process represents the voltage-current relationship as a schematic diagram of a DIDO feedback system;

[0103] Figure 4 Schematic diagram of the conventional DC transmission system of the Shagohuang New Energy Base;

[0104] Figure 5 Frequency domain analysis diagram of oscillations in thermal power plant shafts caused by renewable energy power plants:

[0105] (a) Frequency domain analysis diagram of new energy power station 3; (b) Frequency domain analysis diagram of new energy power station 4;

[0106] (c) Frequency domain analysis diagram of a thermal power plant; (d) Frequency domain analysis diagram of conventional DC transmission;

[0107] Figure 6 Time-domain simulation diagram of oscillations in the thermal power plant shaft system caused by new energy power plants;

[0108] Figure 7 Frequency domain stability analysis diagram of oscillations generated by doubly-fed wind power transmission via series compensation:

[0109] (a) There are no poles in the right half-plane; (b) There are poles in the right half-plane.

[0110] Figure 8 A time-domain simulation diagram of the oscillation generated by the doubly fed wind power through series compensation. Detailed Implementation

[0111] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0112] Please see Figure 1 The multi-port screening method for oscillation risk in new energy bases according to embodiments of the present invention includes the following steps:

[0113] S1. Collect basic data of the new energy base, including the impedance data set of the new energy unit, the grid structure and parameters of the new energy grid connection system, and the operation mode of the new energy grid connection system.

[0114] S2. Using the basic data of the new energy base, a multi-port equivalent model of the new energy base is obtained through vector fitting, impedance aggregation and multi-port model generation process;

[0115] S3. The Nyquist stability criterion is used to assess the oscillation risk of the multi-port equivalent model of the new energy base, and the damping ratio index is used to quantitatively screen the oscillation risk at each port.

[0116] In one possible implementation, the basic data in step S1 is mainly used to describe the equipment, lines, and operating modes of the new energy base. This primarily includes the impedance dataset of the new energy generating units, the grid structure and parameters of the new energy grid-connected system, and the operating modes of the new energy grid-connected system. Further, the impedance dataset of the new energy generating units includes the impedance data of each new energy generating unit under different operating modes within the new energy grid-connected system, thus forming a single-unit impedance dataset. The grid structure and parameters of the new energy grid-connected system include the system's wiring method and the parameters of transmission lines and transformers. The operating modes of the new energy grid-connected system include the output levels of each power generation and transmission device within the system. After generating the basic data, corresponding data is retrieved from the basic data according to different operating conditions for use in the next step of stability analysis.

[0117] In one possible implementation, the vector fitting process in step S2 includes:

[0118] S201. Establish an impedance model for new energy power generation devices;

[0119] S202. The transfer function of the new energy power generation device is fitted using the vector fitting method;

[0120] S203. Divide the transfer function of the new energy power generation device into frequency bands, set the corresponding fitting order in different frequency bands, ignore the control links that have less impact on impedance characteristics than the standard, and only retain the control links that play a dominant role in the impedance characteristics. Simplify the impedance model of the new energy power generation device by dividing it into frequency bands, and realize the frequency band order reduction fitting of the measured impedance of the new energy power generation device.

[0121] Please see Figure 2 , Figure 2This diagram illustrates a multi-port access system for renewable energy power plants, comprising n renewable energy power plants interconnected via a power grid. When analyzing oscillations, ports can be defined at the grid connection points of each power plant for analysis. Taking renewable energy power plant 2 as an example, the portion outside the grid connection port of renewable energy power plant 2 is aggregated into a single grid-side impedance.

[0122] In one possible implementation, the process of impedance polymerization in step S2 includes:

[0123] Select a new energy power station and aggregate the portion of the selected new energy power station other than its grid connection port into a single grid-side impedance;

[0124] For the selected new energy power station, there exists a frequency of f. p Positive sequence disturbance voltage Frequency f n negative sequence disturbance voltage The following node voltage equations exist:

[0125]

[0126] In the formula, N is the number of nodes in the network-side system, and the positive-sequence node admittance matrix is ​​Y. Np The negative-order node admittance matrix is ​​Y. Nn 0 represents the zero vector; This represents the node voltage at the disturbance frequency. This represents the node voltage at the coupling frequency; This represents the current response generated by the negative-sequence disturbance voltage. This represents the negative-sequence current response generated by the positive-sequence perturbation voltage at the coupling frequency. The corresponding current generates a negative sequence disturbance voltage through the electrical network; y 0p This represents the positive-sequence connection admittance between the selected renewable energy power plant and the grid-side system, y 0p Indicates negative-order connectivity admittance;

[0127] The current response at the selected renewable energy power station is calculated using the following formula:

[0128]

[0129] In the formula, To select the positive sequence current of the node response of the new energy power station. To select the negative sequence current of the node response of the new energy power station, Σy 0p This represents the positive-sequence connection admittance y between the selected renewable energy power plant and the grid-side system. 0p Summing all elements in a vector;

[0130] The expressions for solving the positive-sequence and positive-sequence coupling impedances after aggregation of the network-side system are as follows:

[0131]

[0132] The expression for solving negative-order polymerization impedance is as follows:

[0133]

[0134] The pooled impedance of the grid-side system is represented by a 2×2 impedance matrix as follows:

[0135]

[0136] Furthermore, the multi-port model generation process in step S2 includes:

[0137] By analyzing the grid connection ports of different renewable energy power plants within the renewable energy grid-connected system, a port impedance dataset can be obtained. The renewable energy power plant can then be equivalently represented as a 2×2 power plant-side impedance Y. sys1 The system outside the grid connection port is aggregated into a 2×2 equivalent grid-side impedance matrix Y. sys2 This results in a multi-port system;

[0138] After considering the grid-side coupling impedance, the voltage and current relationship of the selected renewable energy power station conforms to the following expression:

[0139]

[0140] Please see Figure 3 The voltage and current relationship of the selected renewable energy power station, as shown in the above formula, can be represented as a dual-input dual-output (DIDO) feedback system. By judging the stability of the DIDO feedback system, the stability of the renewable energy grid-connected system under the corresponding operating mode can be obtained. Figure 2 By performing the above operations on each port in the multi-port access system of the new energy power station shown, multi-port oscillation risk screening can be achieved.

[0141] Due to the large-scale grid-connected renewable energy system, the impedance of renewable energy power plants, DC transmission lines, synchronous machines, reactive power compensation devices, and transmission lines outside the grid connection port is aggregated to obtain the grid-side active admittance Y. sys2 When the grid-side system is unstable, the loop gain of the new energy base feedback system will contain one or more right-half-plane poles, leading to instability in the open-loop system. According to the Nyquist criterion, judging the stability of the system also requires considering the number of right-half-plane poles in the open-loop transfer function. An unstable system may exhibit a Nyquist trajectory that does not circle the point (-1,0), but has right-half-plane poles. In this case, stability and stability margin cannot be judged solely by the trajectory. Existing methods need to be improved and new oscillation risk quantification indicators need to be found.

[0142] In one possible implementation, step S3 applies the Nyquist stability criterion to assess the oscillation risk of the multi-port equivalent model of the new energy base using an improved stability assessment method that takes into account the poles of the right half-plane, including:

[0143] According to the expression of the Nyquist trajectory l(s):

[0144]

[0145] An improved stability assessment method that considers poles in the right half-plane includes the following two points:

[0146] (1) Let N be the number of times the trajectory of l(s) circles the point (-1,0) clockwise; N is positive when it circles clockwise and negative when it circles counterclockwise.

[0147] (2) Solve for the pole distribution of the open-loop transfer function. The expression for the open-loop transfer function is: By solving for det[G(s)]=0, the number of poles in the right half-plane of the open-loop transfer function matrix is ​​obtained and denoted as P;

[0148] The expression for assessing oscillation risk is:

[0149] Z = N + P

[0150] The improved stability assessment method takes into account the influence of the number of poles in the right half-plane on the number of times the Nyquist curve wraps around. When Z = 0, the new energy grid-connected system is stable, and when Z ≠ 0, the new energy grid-connected system is unstable.

[0151] Stability is analyzed by establishing feedback systems at different ports within the system. The hysteresis matrix of the system is defined as I+G(s). Stability here depends on whether all zeros of the hysteresis matrix lie in the left half-plane. The stability margin can be calculated by determining the singular values ​​of the hysteresis matrix. Due to factors such as system topology and parameters, the hysteresis matrix and stability margin differ at different ports. Therefore, for a multi-port system, the conclusions of stability analysis at different ports are consistent, but the specific stability margins obtained will differ. This characteristic can be used to locate the dominant oscillation site.

[0152] In one possible implementation, step S3, which uses the damping ratio index to quantitatively screen the oscillation risk at each port, includes:

[0153] The stability margin at each port is quantified using the damping ratio, and a mode s is solved at each port using the following formula. k :

[0154] s k=-σ k +jω k k = 1, 2, 3, ..., N

[0155] In the formula, N represents the number of system modes; σk is the mode attenuation factor, ω k The frequency corresponding to the mode;

[0156] The damping ratio of a mode is calculated using the following formula:

[0157]

[0158] Where, when ξ i When <0, it indicates that the oscillation mode at the corresponding port is unstable and there is a risk of oscillation.

[0159] When ξ i A value greater than 0 indicates that there is no risk of oscillation at the corresponding port.

[0160] The present invention proposes a multi-port screening method for oscillation risk in new energy bases, which can perform preliminary analysis of system oscillation risk. While achieving accurate location of oscillation-dominant stations, it avoids the influence of the right half-plane poles of the open-loop transfer function on stability judgment.

[0161] The following describes the construction of a conventional DC transmission system for the Shagohuang New Energy Base, using an actual system as a reference. Figure 4 As shown, the system includes renewable energy power plants, thermal power plants, conventional DC transmission lines, substations, and AC transmission lines. Multiple renewable energy power plants form a renewable energy generation cluster. At the grid connection point, the voltage at each power plant is stepped up to 220kV via a substation, and then collected at a 500kV substation via a 220kV line. The renewable energy clusters are interconnected via a 500kV transmission network. Series compensation devices are installed at the output of the doubly-fed wind power system. The thermal power plant is connected to the DC transmission sending end via a 500kV line, with series compensation devices installed at the output. The rated DC voltage of the DC transmission is 500kV, and the receiving-end inverter station is simplified to a single DC source in the model. To simplify the analysis, other parts of the system are simplified to Thevenin equivalent circuits in the form of impedance and voltage source series through an off-grid equivalent method.

[0162] Example 1: Energy-induced oscillation of thermal power plant shaft system

[0163] If the frequency of the oscillating current is complementary to the natural oscillation frequency of the shaft system about the power frequency, resonance may occur, leading to torsional vibration of the unit's shaft system and causing accidents in thermal power units. The thermal power plant model studied in this case study uses a three-mass block shaft system model, therefore exhibiting two natural oscillation modes. Based on the shaft system parameters, the frequencies of these natural oscillation modes can be calculated to be 26Hz and 34Hz, respectively. Frequency domain analysis of shaft system oscillations induced by renewable energy plants is as follows: Figure 5As shown in (a) to (d), the Nyquist curve is drawn with a solid line, corresponding to the left and lower coordinate axes, and the poles are represented by triangles, corresponding to the right and upper coordinate axes. According to the analysis of the attached figure, the electrical oscillation frequency is about 24 / 76Hz. This oscillation frequency is complementary to the natural oscillation frequency of the shaft system. If the oscillation current is conducted to the thermal power plant, it may cause torsional vibration of the unit shaft system.

[0164] The verification was performed in time-domain simulation, and the results are as follows: Figure 6 As shown in the simulation results, the oscillations caused by the interaction between the new energy power station 3 and the power grid spread to the entire system. The current generated by the new energy and the natural oscillation frequency of the shaft system is injected into the stator of the synchronous generator and coupled to the rotor. Through electromechanical interaction, an oscillating torque is generated in the shaft system, which leads to the occurrence of shaft torsional vibration accident. According to the torque simulation results, the 26Hz component of the torque is the largest, which verifies the correctness of the theoretical analysis.

[0165] Example 2: Doubly fed wind power oscillation via series compensation

[0166] To analyze the oscillation problem caused by the doubly-fed wind power transmission via series compensation, a series compensation capacitor was installed at the output of the new energy power station. First, a frequency domain stability analysis was performed using an improved stability criterion, and the results are as follows: Figure 7 As shown in (a) and (b), the Nyquist curve of renewable energy power station 7 bypasses the point (-1,0) at 4Hz and 96Hz, and there are no poles in the right half-plane, indicating system instability. Analysis of the nearby renewable energy power station 2 shows that although its Nyquist curve does not bypass the point (-1,0), it does have poles in the right half-plane, still indicating system instability. Figure 8 The time-domain simulation results shown verify the above conclusions.

[0167] Example 3: Oscillation Risk Screening

[0168] To investigate the oscillation risk under different renewable energy unit output conditions, the DC transmission was set to always deliver 1 pu at full power, and the active power command value of the thermal power plant was 0.5 pu. The output of each renewable energy station within the system varied under different operating modes; detailed output data are shown in Table 1. The method proposed in this embodiment was used to screen the oscillation risk of the case system under different operating modes, and the oscillation results were quantitatively analyzed. The damping ratio results are shown in Table 2.

[0169] Table 1

[0170]

[0171] Table 2

[0172]

[0173] According to the oscillation risk assessment results, there is no oscillation risk in operation modes 1-4 and 6-10, and the new energy can send power according to the operation mode command. For operation mode 5, the damping ratio obtained from the analysis is negative, and there is an oscillation risk.

[0174] Another embodiment of the present invention also proposes a multi-port screening system for oscillation risk in new energy bases, comprising:

[0175] The basic data collection module is used to collect basic data of the new energy base. The basic data of the new energy base includes the impedance data set of the new energy units, the grid structure and parameters of the new energy grid connection system, and the operation mode of the new energy grid connection system.

[0176] The multi-port equivalent model building module is used to obtain the multi-port equivalent model of the new energy base by using the basic data of the new energy base through vector fitting, impedance aggregation and multi-port model generation process.

[0177] The oscillation risk assessment and screening module is used to assess the oscillation risk of the multi-port equivalent model of the new energy base using the Nyquist stability criterion, and to quantitatively screen the oscillation risk at each port using the damping ratio index.

[0178] In one possible implementation, when the basic data collection module collects basic data of the new energy base, the impedance dataset of the new energy units includes the impedance data of each new energy unit in the new energy grid connection system under different operating modes.

[0179] The grid structure and parameters of a new energy grid-connected system include the system's wiring method and the parameters of transmission lines and transformers;

[0180] The operation mode of a new energy grid-connected system includes the output level of each power generation device and transmission device within the system.

[0181] In one possible implementation, the multi-port equivalent model building module is executed during the vector fitting process:

[0182] Establish an impedance model for new energy power generation devices;

[0183] The transfer function of the new energy power generation device is fitted using a vector fitting method.

[0184] The transfer function of the new energy power generation device is divided into frequency bands, and a corresponding fitting order is set for each frequency band. The control links that have less impact on impedance characteristics than the standard are ignored, and only the control links that play a dominant role in the impedance characteristics are retained. The impedance model of the new energy power generation device is simplified by frequency band division, so as to realize the frequency band order reduction fitting of the measured impedance of the new energy power generation device.

[0185] In one possible implementation, the multi-port equivalent model building module is executed during the impedance aggregation process:

[0186] Select a new energy power station and aggregate the portion of the selected new energy power station other than its grid connection port into a single grid-side impedance;

[0187] For the selected new energy power station, there exists a frequency of f. p Positive sequence disturbance voltage Frequency f n negative sequence disturbance voltage The following node voltage equations exist:

[0188]

[0189] In the formula, N is the number of nodes in the network-side system, and the positive-sequence node admittance matrix is ​​Y. Np The negative-order node admittance matrix is ​​Y. Nn 0 represents the zero vector; This represents the node voltage at the disturbance frequency. This represents the node voltage at the coupling frequency; This represents the current response generated by the negative-sequence disturbance voltage. This represents the negative-sequence current response generated by the positive-sequence perturbation voltage at the coupling frequency. The corresponding current generates a negative sequence disturbance voltage through the electrical network; y 0p This represents the positive-sequence connection admittance between the selected renewable energy power plant and the grid-side system, y 0p Indicates negative-order connectivity admittance;

[0190] The current response at the selected renewable energy power station is calculated using the following formula:

[0191]

[0192] In the formula, To select the positive sequence current of the node response of the new energy power station. To select the negative sequence current of the node response of the new energy power station, Σy 0p This represents the positive-sequence connection admittance y between the selected renewable energy power plant and the grid-side system. 0p Summing all elements in a vector;

[0193] The expressions for solving the positive-sequence and positive-sequence coupling impedances after aggregation of the network-side system are as follows:

[0194]

[0195] The expression for solving negative-order polymerization impedance is as follows:

[0196]

[0197] The pooled impedance of the grid-side system is represented by a 2×2 impedance matrix as follows:

[0198]

[0199] In one possible implementation, the multiport equivalent model building module is executed during the multiport model generation process:

[0200] By analyzing the grid connection ports of different renewable energy power plants within the renewable energy grid-connected system, a port impedance dataset is obtained, and the renewable energy power plant is equivalently represented as a 2×2 power plant-side impedance Y. sys1 The system outside the grid connection port is aggregated into a 2×2 equivalent grid-side impedance matrix Y. sys2 This results in a multi-port system;

[0201] After considering the grid-side coupling impedance, the voltage and current relationship of the selected renewable energy power station conforms to the following expression:

[0202]

[0203] The voltage and current relationship of the selected renewable energy power station is represented as a dual-input dual-output (DIDO) feedback system. By judging the stability of the DIDO feedback system, the stability of the renewable energy grid-connected system under the corresponding operating mode is obtained.

[0204] In one possible implementation, when the oscillation risk assessment and screening module uses the Nyquist stability criterion to assess the oscillation risk of the multi-port equivalent model of the new energy base, it follows the expression of the Nyquist trajectory l(s):

[0205]

[0206] Let N be the number of times the trajectory of l(s) circles the point (-1,0) clockwise; N is positive when it circles clockwise and negative when it circles counterclockwise.

[0207] Solve for the pole distribution of the open-loop transfer function. The expression for the open-loop transfer function is: By solving for det[G(s)]=0, the number of poles in the right half-plane of the open-loop transfer function matrix is ​​obtained and denoted as P;

[0208] The expression for assessing oscillation risk is:

[0209] Z = N + P

[0210] Taking into account the influence of the number of poles in the right half-plane on the number of times the Nyquist curve wraps, the new energy grid-connected system is stable when Z = 0, and unstable when Z ≠ 0.

[0211] In one possible implementation, when the oscillation risk assessment and screening module uses the damping ratio index to quantitatively screen the oscillation risk at each port, it also uses the damping ratio to quantify the stability margin at each port, and solves for a mode s at each port using the following formula. k :

[0212] s k =-σ k +jω k k = 1, 2, 3, ..., N

[0213] In the formula, N represents the number of system modes; σk is the mode attenuation factor, ω k The frequency corresponding to the mode;

[0214] The damping ratio of a mode is calculated using the following formula:

[0215]

[0216] Where, when ξ i When <0, it indicates that the oscillation mode at the corresponding port is unstable and there is a risk of oscillation.

[0217] When ξ i A value greater than 0 indicates that there is no risk of oscillation at the corresponding port.

[0218] Another embodiment of the present invention also proposes an electronic device, including a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the aforementioned multi-port screening method for oscillation risk of new energy bases.

[0219] Another embodiment of the present invention also proposes a computer-readable storage medium storing at least one instruction, which, when executed by a processor, implements the multi-port screening method for oscillation risks in new energy bases.

[0220] The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable storage medium can include any entity or device capable of carrying the computer program code, a medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals. For ease of explanation, the above content only shows the parts related to the embodiments of the present invention; for specific technical details not disclosed, please refer to the method section of the embodiments of the present invention. This computer-readable storage medium is non-transitory and can be stored in storage devices formed by various electronic devices, enabling the execution process described in the method of the embodiments of the present invention.

[0221] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0222] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0223] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0224] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0225] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A multi-port screening method for oscillation risk in new energy bases, characterized in that, include: Collect basic data of new energy bases, including impedance data of new energy units, grid structure and parameters of new energy grid-connected systems, and operation mode of new energy grid-connected systems. By utilizing the basic data of the new energy base, a multi-port equivalent model of the new energy base is obtained through vector fitting, impedance aggregation, and multi-port model generation processes. The Nyquist stability criterion was used to assess the oscillation risk of the multi-port equivalent model of the new energy base, and the damping ratio index was used to quantitatively screen the oscillation risk at each port.

2. The multi-port screening method for oscillation risk in new energy bases according to claim 1, characterized in that, The impedance dataset of the new energy generating units includes impedance data of each new energy generating unit in the new energy grid-connected system under different operating modes; The grid structure and parameters of a new energy grid-connected system include the system's wiring method and the parameters of transmission lines and transformers; The operation mode of a new energy grid-connected system includes the output level of each power generation device and transmission device within the system.

3. The multi-port screening method for oscillation risk in new energy bases according to claim 1, characterized in that, In the step of obtaining a multi-port equivalent model of the new energy base by utilizing its basic data through vector fitting, impedance aggregation, and multi-port model generation, the vector fitting process includes: Establish an impedance model for new energy power generation devices; The transfer function of the new energy power generation device is fitted using a vector fitting method. The transfer function of the new energy power generation device is divided into frequency bands, and a corresponding fitting order is set for each frequency band. The control links that have less impact on impedance characteristics than the standard are ignored, and only the control links that play a dominant role in the impedance characteristics are retained. The impedance model of the new energy power generation device is simplified by frequency band division, so as to realize the frequency band order reduction fitting of the measured impedance of the new energy power generation device.

4. The multi-port screening method for oscillation risk in new energy bases according to claim 1, characterized in that, In the step of obtaining a multi-port equivalent model of the new energy base by using basic data from the new energy base through vector fitting, impedance aggregation, and multi-port model generation, the impedance aggregation process includes: Select a new energy power station and aggregate the portion of the selected new energy power station other than its grid connection port into a single grid-side impedance; For the selected new energy power station, there exists a frequency of f. p Positive sequence disturbance voltage Frequency f n negative sequence disturbance voltage The following node voltage equations exist: In the formula, N is the number of nodes in the network-side system, and the positive-sequence node admittance matrix is ​​Y. Np The negative-order node admittance matrix is ​​Y. Nn 0 represents the zero vector; This represents the node voltage at the disturbance frequency. This represents the node voltage at the coupling frequency; This represents the current response generated by the negative-sequence disturbance voltage. This represents the negative-sequence current response generated by the positive-sequence perturbation voltage at the coupling frequency. The corresponding current generates a negative sequence disturbance voltage through the electrical network; y 0p This represents the positive-sequence connection admittance between the selected renewable energy power plant and the grid-side system, y 0p Indicates negative-order connectivity admittance; The current response at the selected renewable energy power station is calculated using the following formula: In the formula, To select the positive sequence current of the node response of the new energy power station. To select the negative sequence current of the node response of the new energy power station, Σy 0p This represents the positive-sequence connection admittance y between the selected renewable energy power plant and the grid-side system. 0p Summing all elements in a vector; The expressions for solving the positive-sequence and positive-sequence coupling impedances after aggregation of the network-side system are as follows: The expression for solving negative-order polymerization impedance is as follows: The pooled impedance of the grid-side system is represented by a 2×2 impedance matrix as follows:

5. The multi-port screening method for oscillation risk in new energy bases according to claim 4, characterized in that, In the step of obtaining a multi-port equivalent model of the new energy base by using basic data from the new energy base through vector fitting, impedance aggregation, and multi-port model generation, the multi-port model generation process includes: By analyzing the grid connection ports of different renewable energy power plants within the renewable energy grid-connected system, a port impedance dataset is obtained, and the renewable energy power plant is equivalently represented as a 2×2 power plant-side impedance Y. sys1 The system outside the grid connection port is aggregated into a 2×2 equivalent grid-side impedance matrix Y. sys2 This results in a multi-port system; After considering the grid-side coupling impedance, the voltage and current relationship of the selected renewable energy power station conforms to the following expression: The voltage and current relationship of the selected renewable energy power station is represented as a dual-input dual-output (DIDO) feedback system. By judging the stability of the DIDO feedback system, the stability of the renewable energy grid-connected system under the corresponding operating mode is obtained.

6. The multi-port screening method for oscillation risk in new energy bases according to claim 5, characterized in that, The steps for assessing oscillation risk using the Nyquist stability criterion in the multi-port equivalent model of the new energy base include: According to the expression of the Nyquist trajectory l(s): Let N be the number of times the trajectory of l(s) circles the point (-1,0) clockwise; N is positive when it circles clockwise and negative when it circles counterclockwise. Solve for the pole distribution of the open-loop transfer function. The expression for the open-loop transfer function is: By solving for det[G(s)]=0, the number of poles in the right half-plane of the open-loop transfer function matrix is ​​obtained and denoted as P; The expression for assessing oscillation risk is: Z = N + P Taking into account the influence of the number of poles in the right half-plane on the number of times the Nyquist curve wraps, the new energy grid-connected system is stable when Z = 0, and unstable when Z ≠ 0.

7. The multi-port screening method for oscillation risk in new energy bases according to claim 1, characterized in that, The steps for quantitatively screening the oscillation risk at each port using the damping ratio index include: The stability margin at each port is quantified using the damping ratio, and a mode s is solved at each port using the following formula. k : s k G-σ k +jω k ,kJ1,2,3,...,N In the formula, N represents the number of system modes; σk is the mode attenuation factor, ω k The frequency corresponding to the mode; The damping ratio of a mode is calculated using the following formula: Where, when ξ i When <0, it indicates that the oscillation mode at the corresponding port is unstable and there is a risk of oscillation. When ξ i A value greater than 0 indicates that there is no risk of oscillation at the corresponding port.

8. A multi-port screening system for oscillation risk in new energy bases, characterized in that, include: The basic data collection module is used to collect basic data of the new energy base. The basic data of the new energy base includes the impedance data set of the new energy units, the grid structure and parameters of the new energy grid connection system, and the operation mode of the new energy grid connection system. The multi-port equivalent model building module is used to obtain the multi-port equivalent model of the new energy base by using the basic data of the new energy base through vector fitting, impedance aggregation and multi-port model generation process. The oscillation risk assessment and screening module is used to assess the oscillation risk of the multi-port equivalent model of the new energy base using the Nyquist stability criterion, and to quantitatively screen the oscillation risk at each port using the damping ratio index.

9. The multi-port screening system for oscillation risk in new energy bases according to claim 8, characterized in that, When collecting basic data from the new energy base, the basic data collection module includes impedance data of each new energy unit in the new energy grid connection system under different operating modes. The grid structure and parameters of a new energy grid-connected system include the system's wiring method and the parameters of transmission lines and transformers; The operation mode of a new energy grid-connected system includes the output level of each power generation device and transmission device within the system.

10. The multi-port screening system for oscillation risk in new energy bases according to claim 8, characterized in that, The multi-port equivalent model building module is executed during the vector fitting process: Establish an impedance model for new energy power generation devices; The transfer function of the new energy power generation device is fitted using a vector fitting method. The transfer function of the new energy power generation device is divided into frequency bands, and a corresponding fitting order is set for each frequency band. The control links that have less impact on impedance characteristics than the standard are ignored, and only the control links that play a dominant role in the impedance characteristics are retained. The impedance model of the new energy power generation device is simplified by frequency band division, so as to realize the frequency band order reduction fitting of the measured impedance of the new energy power generation device.

11. The multi-port screening system for oscillation risk in new energy bases according to claim 8, characterized in that, The multi-port equivalent model building module is executed during the impedance aggregation process: Select a new energy power station and aggregate the portion of the selected new energy power station other than its grid connection port into a single grid-side impedance; For the selected new energy power station, there exists a frequency of f. p Positive sequence disturbance voltage Frequency f n negative sequence disturbance voltage The following node voltage equations exist: In the formula, N is the number of nodes in the network-side system, and the positive-sequence node admittance matrix is ​​Y. Np The negative-order node admittance matrix is ​​Y. Nn 0 represents the zero vector; This represents the node voltage at the disturbance frequency. This represents the node voltage at the coupling frequency; This represents the current response generated by the negative-sequence disturbance voltage. This represents the negative-sequence current response generated by the positive-sequence perturbation voltage at the coupling frequency. The corresponding current generates a negative sequence disturbance voltage through the electrical network; y 0p This represents the positive-sequence connection admittance between the selected renewable energy power plant and the grid-side system, y 0p Indicates negative-order connectivity admittance; The current response at the selected renewable energy power station is calculated using the following formula: In the formula, To select the positive sequence current of the node response of the new energy power station. To select the negative sequence current of the node response of the new energy power station, Σy 0p This represents the positive-sequence connection admittance y between the selected renewable energy power plant and the grid-side system. 0p Summing all elements in a vector; The expressions for solving the positive-sequence and positive-sequence coupling impedances after aggregation of the network-side system are as follows: The expression for solving negative-order polymerization impedance is as follows: The pooled impedance of the grid-side system is represented by a 2×2 impedance matrix as follows:

12. The multi-port screening system for oscillation risk in new energy bases according to claim 11, characterized in that, The multi-port equivalent model building module is executed during the multi-port model generation process: By analyzing the grid connection ports of different renewable energy power plants within the renewable energy grid-connected system, a port impedance dataset is obtained, and the renewable energy power plant is equivalently represented as a 2×2 power plant-side impedance Y. sys1 The system outside the grid connection port is aggregated into a 2×2 equivalent grid-side impedance matrix Y. sys2 This results in a multi-port system; After considering the grid-side coupling impedance, the voltage and current relationship of the selected renewable energy power station conforms to the following expression: The voltage and current relationship of the selected renewable energy power station is represented as a dual-input dual-output (DIDO) feedback system. By judging the stability of the DIDO feedback system, the stability of the renewable energy grid-connected system under the corresponding operating mode is obtained.

13. The multi-port screening system for oscillation risk in new energy bases according to claim 12, characterized in that, When the oscillation risk assessment and screening module uses the Nyquist stability criterion to assess the oscillation risk of the multi-port equivalent model of the new energy base, it follows the expression of the Nyquist trajectory l(s): Let N be the number of times the trajectory of l(s) circles the point (-1,0) clockwise; N is positive when it circles clockwise and negative when it circles counterclockwise. Solve for the pole distribution of the open-loop transfer function. The expression for the open-loop transfer function is: By solving for det[G(s)]=0, the number of poles in the right half-plane of the open-loop transfer function matrix is ​​obtained and denoted as P; The expression for assessing oscillation risk is: Z = N + P Taking into account the influence of the number of poles in the right half-plane on the number of times the Nyquist curve wraps, the new energy grid-connected system is stable when Z = 0, and unstable when Z ≠ 0.

14. The multi-port screening system for oscillation risk in new energy bases according to claim 8, characterized in that, When the oscillation risk assessment and screening module uses the damping ratio index to quantitatively screen the oscillation risk at each port, it uses the damping ratio to quantify the stability margin at each port, and solves for a mode s at each port using the following formula. k : s k G-σ k +jω k ,kJ1,2,3,...,N In the formula, N represents the number of system modes; σk is the mode attenuation factor, ω k The frequency corresponding to the mode; The damping ratio of a mode is calculated using the following formula: Where, when ξ i When <0, it indicates that the oscillation mode at the corresponding port is unstable and there is a risk of oscillation. When ξ i A value greater than 0 indicates that there is no risk of oscillation at the corresponding port.

15. An electronic device, characterized in that, It includes a processor and a memory, the processor being used to execute a computer program stored in the memory to implement the multi-port screening method for oscillation risk of new energy bases as described in any one of claims 1 to 7.

16. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one instruction, which, when executed by a processor, implements the multi-port screening method for oscillation risk of new energy bases as described in any one of claims 1 to 7.

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