Standardized Equivalent Modeling Method and Apparatus for Wind Farms Under Fault Conditions

Abstract

This application relates to a standardized equivalent modeling method and apparatus for wind farms under fault conditions. The method includes: firstly grouping the wind turbines into groups based on their equivalent electrical distances to the grid connection point, resulting in a first turbine group; secondly grouping the wind turbines within each first turbine group into second turbine groups based on their wind speed and fault steady-state terminal voltage; and thirdly constructing an equivalent wind farm model for each second turbine group based on its corresponding equivalent turbine parameters and equivalent line parameters. The model is used to infer the current and voltage responses of the target turbines from the back-conversion boundary conditions. Knowing the electrical boundary conditions of the grid connection point allows for the inversion of the current and voltage responses of any target turbine within the group, which helps in identifying abnormal extreme values ​​in the simulation.

Description

Technical Field

[0001] This application relates to the field of new energy technology, and in particular to a standardized equivalent modeling method and apparatus for wind farms under fault conditions. Background Technology

[0002] With the continuous expansion of wind power grid connection, large-scale power electronic wind turbine units, represented by doubly-fed induction generators (DFIGs) and direct-drive wind turbines, are gradually becoming an important component of the power system. Compared with traditional synchronous machines, wind turbine units are connected to the grid through converters, and their fault transient response is significantly affected by control strategies, operating conditions, and converter current-limiting characteristics, resulting in significant changes in the system's frequency and voltage regulation capabilities and transient oscillation characteristics. Under large-scale wind power grid connection conditions, the overall fault response of wind farms differs significantly from that of traditional synchronous machine-dominated systems. Wind farm aggregation modeling has become an important foundation for conducting power system fault condition simulation and transient calculations.

[0003] Traditional methods use a single-unit multiplication approach, multiplying the number of turbines by the number of turbines to represent the entire wind farm. While this simplifies modeling, it fails to adequately consider the operational differences and topology within the wind farm, making it unsuitable for high-precision transient simulations. Furthermore, multi-unit equivalent modeling suffers from reliance on post-fault simulation data and neglects the internal responses of the wind farm. Summary of the Invention

[0004] Therefore, it is necessary to provide a standardized equivalent modeling method, apparatus, computer equipment, computer-readable storage medium, and computer program product for wind farms under fault conditions that can solve the above-mentioned technical problems.

[0005] Firstly, this application provides a standardized equivalent modeling method for wind farms under fault conditions. The method includes: Obtain the equivalent electrical distance from each of the multiple wind turbine units to the grid connection point; Based on the equivalent electrical distances, the wind turbines are first grouped to obtain the first turbine group to which the wind turbines belong; wherein, the dispersion of the equivalent electrical distances of the multiple wind turbines in the first turbine group satisfies the elbow screening condition with respect to the number of groups in the first turbine group. For each wind turbine in the first unit group, the wind turbine is further divided into second groups based on the wind speed and fault steady-state terminal voltage of the wind turbine to obtain the second unit group to which the wind turbine belongs. For each of the second unit groups, an equivalent wind farm model is constructed based on the equivalent unit parameters and equivalent line parameters corresponding to the second unit group; wherein, the equivalent wind farm model is used to solve the current response and voltage response of the target unit by inferring the boundary conditions of the target unit.

[0006] Secondly, this application also provides a standardized equivalent modeling device for wind farms under fault conditions. The device includes: The acquisition module is used to obtain the equivalent electrical distance from each of the multiple wind turbine units to the grid connection point; A primary grouping module is used to perform a first grouping of each wind turbine based on the equivalent electrical distance, to obtain a first unit group to which the wind turbine belongs; wherein, the dispersion of the equivalent electrical distances of multiple wind turbines in the first unit group satisfies the elbow screening condition with respect to the number of groups in the first unit group. The secondary grouping module is used to perform a second grouping of the wind turbines in each of the first unit groups based on the wind speed and fault steady-state terminal voltage of the wind turbines, so as to obtain the second unit group to which the wind turbines belong. The modeling module is used to construct an equivalent wind farm model for each of the second unit groups based on the equivalent unit parameters and equivalent line parameters corresponding to the second unit group; wherein, the equivalent wind farm model is used to solve the current response and voltage response of the target unit by back-inferring the boundary conditions of the target unit.

[0007] Thirdly, this application also provides a computer device. The computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the above method steps.

[0008] Fourthly, this application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program thereon, which, when executed by a processor, implements the above method steps.

[0009] Fifthly, this application also provides a computer program product. The computer program product includes a computer program that, when executed by a processor, implements the above method steps.

[0010] The aforementioned standardized equivalent modeling method, device, computer equipment, storage medium, and computer program products for wind farms under fault conditions obtain the equivalent electrical distance from each of the multiple wind turbine units to the grid connection point, quantify the positional differences of each unit in the electrical topology, and provide a physically meaningful clustering basis for subsequent grouping.

[0011] Based on the equivalent electrical distances, each wind turbine is first grouped to obtain the first unit group to which the wind turbine belongs. The dispersion of the equivalent electrical distances of multiple wind turbines in the first unit group satisfies the elbow screening condition with the number of groups in the first unit group. Firstly, the elbow screening condition automatically determines the optimal number of groups, avoiding subjective errors caused by manually setting the number of groups. Secondly, it ensures that the electrical distance dispersion of units within the same group is small (i.e., the impedance to the grid connection point is similar), thereby ensuring the voltage drop depth of units within the group during grid disturbances.

[0012] For each wind turbine in the first unit group, the wind turbines are grouped a second time based on the wind speed and fault steady-state terminal voltage of the wind turbines to obtain the second unit group to which the wind turbines belong. On the basis of similar electrical position, the differences in operating conditions (wind speed) and fault response characteristics (terminal voltage) are further distinguished, realizing dual fine grouping of position + state, which helps to improve the accuracy of transient simulation.

[0013] For each second unit group, an equivalent wind farm model is constructed based on the equivalent unit parameters and equivalent line parameters corresponding to the second unit group. Firstly, each second unit group is ultimately represented by an equivalent machine, significantly reducing the system order and simulation computational load. Secondly, the equivalent model simultaneously includes unit parameters (capacity, inertia, control parameters) and line parameters (equivalent impedance), accurately reproducing the power external characteristics from the units within the group to the grid connection point. Thirdly, the finer-grained grouping (two groupings) allows the equivalent model to maintain computational efficiency while achieving significantly higher accuracy than single-machine multiplication or single-grouping methods.

[0014] Among them, the wind farm equivalent model is used to solve the current and voltage responses of the target unit by inferring the boundary conditions of the target unit. On the one hand, when the electrical boundary conditions of the grid connection point are known, the current and voltage responses of any target unit inside can be inferred, which helps to find abnormal extreme values ​​in the simulation. On the other hand, without modeling each unit separately, the detailed internal response of a specific unit under fault or disturbance can be quickly obtained, which is suitable for scenarios such as protection setting verification and fault source analysis. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating a standardized equivalent modeling method for wind farms under fault conditions in one embodiment. Figure 2 Here is a radial wiring diagram for one embodiment; Figure 3 Here is a trunk wiring diagram for one embodiment; Figure 4 This is a schematic diagram of an external fault in a wind farm in one embodiment; Figure 5 This is a structural block diagram of a wind farm standardized equivalent modeling device for fault conditions in one embodiment. Figure 6 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0017] In one embodiment, such as Figure 1 As shown, a standardized equivalent modeling method for wind farms under fault conditions is provided, specifically including: S101, obtain the equivalent electrical distance from each of the multiple wind turbine units to the grid connection point.

[0018] Among them, wind turbine units represent complete units that convert wind energy into electrical energy, typically including wind turbines (blades, hubs), transmission systems (main shaft, gearbox—direct drive units have no gearbox), generators (asynchronous / doubly fed / permanent magnet synchronous), converters, transformers (panel substations), and controllers.

[0019] The grid connection point represents the point where the combined electrical energy from all wind turbines within the wind farm is connected to the external power grid. In the main electrical wiring diagram of a wind farm, this is typically the high-voltage side busbar of the substation.

[0020] Equivalent electrical distance can represent the comprehensive per-unit value of the impedance of all electrical components (such as collector cables / overhead lines, busbars, step-up transformers, switch stations, etc.) from the high-voltage side of the wind turbine transformer box (or the turbine outlet) to the grid connection point.

[0021] The calculation process for the equivalent electrical distance of wind turbines differs depending on the wind turbine topology. For wind turbines in a radial topology, the equivalent electrical distance is defined as the path impedance of the line between the turbine's access node and the grid connection point. For a trunk topology, the equivalent electrical distance is defined as the cumulative value of the line impedance along the collector line topology path between the turbine's access node and the collector bus.

[0022] Specifically, obtaining the equivalent electrical distance from each of the multiple wind turbines to the grid connection point includes: determining the topology to which each of the multiple wind turbines belongs; for wind turbines with a radial topology, determining the line path impedance between the wind turbine's access node and the grid connection point as the equivalent electrical distance from the wind turbine to the grid connection point; for wind turbines with a trunk topology, determining the accumulated value of the line impedance along the collector line topology path from the wind turbine's access node to the collector bus as the equivalent electrical distance from the wind turbine to the grid connection point.

[0023] Specifically, obtaining the equivalent electrical distance from each of the multiple wind turbine units to the grid connection point includes: directly obtaining the equivalent electrical distance from each of the multiple wind turbine units to the grid connection point from the database.

[0024] The differences in the electrical topology of each unit were quantified, providing a physically meaningful clustering basis for subsequent grouping.

[0025] S102, based on each equivalent electrical distance, the wind turbine units are first grouped to obtain the first unit group to which the wind turbine units belong.

[0026] Among them, the dispersion of the equivalent electrical distances of multiple wind turbines in the first unit group satisfies the elbow screening condition with respect to the number of groups in the first unit group.

[0027] The first unit group represents an intermediate grouping obtained after preliminary clustering of all wind turbines based on the single metric of equivalent electrical distance. Wind turbines within each first unit group have similar equivalent electrical distances to the grid connection point. The first unit group can serve as the basic unit for subsequent second-stage clustering. At this stage, only the electrical location similarity of the units is considered; operating conditions (wind speed) or fault response characteristics are not yet differentiated.

[0028] The degree of dispersion is a statistical indicator representing the difference in the equivalent electrical distance between wind turbines within a given group of turbines. The smaller the degree of dispersion, the closer the electrical distance between the turbines in the group (i.e., the more consistent the impedance to the grid connection point).

[0029] The number of groups indicates how many primary turbine groups are divided into for all wind turbines in a single clustering operation. This value is a positive integer. If the number of groups is too small, the equivalent model is simple and computationally inexpensive, but it may mix turbines with large electrical distance differences together, resulting in lower accuracy and failing to reflect the voltage differences between near-end and far-end turbines. If the number of groups is too large, the accuracy is high, but the number of equivalent turbines is close to the original number of turbines, negating the purpose of order reduction and potentially leading to overfitting.

[0030] Elbow selection criteria can be used in cluster analysis. As the number of clusters increases, the overall dispersion monotonically decreases, but the rate of decrease slows dramatically, forming an "elbow inflection point." The number of clusters corresponding to this inflection point is the elbow selection criterion, or the optimal number of clusters.

[0031] Specifically, based on each equivalent electrical distance, each wind turbine is first grouped to obtain the first unit group to which the wind turbine belongs. This includes: obtaining the optimal number of groups that meet the elbow screening conditions; and based on the optimal number of groups and each equivalent electrical distance, each wind turbine is first grouped to obtain the first unit group to which the wind turbine belongs. The number of the first unit group is the optimal number of groups.

[0032] Specifically, based on each equivalent electrical distance, the wind turbines are first grouped to obtain the first unit group to which the wind turbines belong. This includes: obtaining multiple candidate grouping schemes, with different numbers of groups among the candidate grouping schemes; pre-grouping each wind turbine based on each candidate grouping scheme to obtain the electrical distance error within the overall category for each candidate grouping scheme; determining the optimal number of groups among each candidate grouping scheme based on the mapping relationship sequence between the electrical distance error within the overall category and the number of groups; wherein, the point of the optimal number of groups in the mapping relationship sequence is the maximum point of the absolute value of the second difference of the mapping relationship sequence; and performing the first grouping of each wind turbine based on the optimal number of groups and each equivalent electrical distance to obtain the first unit group to which the wind turbines belong.

[0033] First, the optimal number of clusters is automatically determined by elbow screening conditions, avoiding subjective errors caused by manually setting the number of clusters. Second, it ensures that the electrical distance dispersion of units within the same cluster is small (i.e., the impedance to the grid connection point is similar), thereby ensuring the voltage drop depth of units within the cluster during grid disturbances.

[0034] S103, for each wind turbine in the first unit group, based on the wind speed and fault steady-state terminal voltage of the wind turbine, the wind turbine is divided into a second group to obtain the second unit group to which the wind turbine belongs.

[0035] Wind speed refers to the speed of the natural airflow that blows towards the rotor of the wind turbine, driving it to rotate and generate electricity. Wind speed determines the power output of the unit and directly determines the active power output of the wind turbine. Under different wind speeds, the unit's rotational speed, pitch angle, and converter control state are all different, resulting in significant differences in its active / reactive current response characteristics during grid faults (such as voltage drops).

[0036] Fault steady-state terminal voltage refers to the effective value of the voltage measured at the wind turbine terminals when the power system experiences a fault and enters a steady-state phase.

[0037] The second unit group can be represented as the final grouping obtained after classifying wind turbines within each first unit group based on two indicators: wind speed and fault steady-state terminal voltage.

[0038] Specifically, S103 includes: for each wind turbine in the first unit group, the current fault response mode of the wind turbine can be determined based on the relationship between wind speed and fault steady-state terminal voltage; and the second unit group to which the wind turbine belongs can be determined based on the fault response mode.

[0039] For example, based on wind speed and fault steady-state terminal voltage The quantitative relationship between (per-unit values) is used to determine the differences in reactive power support capacity, active power transmission capacity, and DC side control status of wind turbine units during faults, thereby further classifying the unit fault response modes and categorizing them into the following four types: I. When and At that time, This means that the wind turbine enters the reactive power support priority control mode, and the reactive current is determined by the national standard formula. During the fault, the wind turbine continues to maintain DC voltage control, and the direct-drive wind turbine can deliver active power normally. The DC voltage can remain stable, but there will be short-term oscillations in the early stage of the fault and after the fault is cleared.

[0040] II. When and At that time, This means that the wind turbine enters the reactive power support priority control mode. The reactive current is determined by the national standard formula. During the fault, the active current is determined by the reactive current and the inverter capacity. The active power output in the fault steady state is less than the steady state value before the fault. After the fault is cleared, the active power will also return to near the steady state value before the fault the moment the voltage recovers.

[0041] III. When and At that time, This means that the wind turbine enters the reactive power support priority control mode. The reactive current is determined by the national standard formula. During the fault, the active current is also determined by the reactive current and the inverter capacity. The active power output in the fault steady state is less than the steady state value before the fault. However, after the fault is cleared, the active power is still lower than the steady state value before the fault when the voltage recovers. It takes a period of time to recover to the steady state value before the fault.

[0042] IV. When When the fault drop is relatively shallow, the maximum capacity of the inverter is generally... , Therefore, at this time, the reactive current is maintained under the control of normal operation. The wind turbine often adopts unity power factor control, that is, the reactive current control reference value is 0, and the active current is also maintained under DC voltage control. The response is similar to the first case.

[0043] in, To provide reactive power support, the upper limit of the active current allowed to pass through the converter; This refers to the active current during normal steady-state operation before the fault. This is the reference value for the active power output of the wind turbine. This is the reference value of active current obtained from DC voltage control during the fault period; the aforementioned current values ​​can all be obtained from wind speed. It is derived. This is the upper limit of the current allowed through the converter.

[0044] Specifically, S103 includes: for each wind turbine in the first unit group, obtaining the wind turbine fault steady-state voltage and wind speed; determining the wind turbine fault steady-state terminal voltage according to the calculation path matched by the topology to which the wind turbine belongs and the fault steady-state voltage; and determining the second unit group to which the wind turbine belongs based on the fault steady-state terminal voltage and wind speed.

[0045] Based on similar electrical locations, the differences in operating conditions (wind speed) and fault response characteristics (terminal voltage) are further distinguished, achieving dual fine-grained grouping of location and state, which helps to improve the accuracy of transient simulation.

[0046] S104. For each second unit group, construct an equivalent wind farm model for each second unit group based on the equivalent unit parameters and equivalent line parameters corresponding to the second unit group.

[0047] Among them, the wind farm equivalent model is used to solve the current response and voltage response of the target unit by inferring the boundary conditions from the target unit.

[0048] The equivalent unit parameters are the comprehensive parameters assigned to an equivalent unit when multiple actual wind turbines within a second unit group are aggregated into a single equivalent unit. It is the result of merging the original parameters of all units within the group according to certain physical principles (such as capacity weighting and per-unit averaging).

[0049] Specifically, the equivalent unit parameters include: the active power, reactive power, damping coefficient, inertia coefficient, motor reactance, and motor resistance of the second unit group. These equivalent unit parameters can be obtained by using the active power, reactive power, damping coefficient, inertia coefficient, motor reactance, and motor resistance of any wind turbine in the second unit group, through a capacity-weighted method, as shown in the following formula: ; in, This refers to the number of wind turbine units within the second unit. , , , , , The first The active power, reactive power, damping coefficient, inertia coefficient, motor reactance, and motor resistance outputs of the typhoon generator set. , , , , , These represent the active power, reactive power, damping coefficient, inertia coefficient, motor reactance, and motor resistance of the output corresponding to the second unit group, respectively.

[0050] Equivalent line parameters represent the equivalent impedance (resistance + reactance) and ground admittance obtained after aggregating the power collection lines, transformer substations, and other electrical connection components of each wind turbine in the second unit group to the grid connection point.

[0051] Specifically, in a trunk-type topology, the equivalent line parameters of the units are first calculated by combining the operating current of each unit's access node and the parameters of the collector lines. These parameters are used to characterize the actual line voltage drop and power transmission characteristics of the units under fault conditions.

[0052] ; ; ; in, , , These are the equivalent line parameters for wind turbine units WTG-1, WTG-2, and WTG-M, respectively.

[0053] Based on this, regardless of whether the actual wind farm adopts a radial or trunk structure, the wind farm's collector network is uniformly equivalent to a parallel radial structure where each turbine connects to the collecting bus via independent branches, thus achieving unified modeling of different collector network topologies. For turbines within the same cluster, equivalent processing of the collector lines is performed according to the parallel topology relationship. Combining the equivalent line parameters corresponding to the operating state of each turbine, the equivalent line parameters corresponding to the second turbine group are calculated based on the principle of equal power loss. This ensures the consistency of power loss characteristics of the collector network before and after the equivalent value.

[0054] ; A wind farm equivalent model represents a simplified mathematical model of the original wind farm (which may contain dozens or even hundreds of turbines). It consists of multiple equivalent turbines (each corresponding to a second turbine group) + equivalent transmission lines + grid connection points, and is used to significantly reduce the amount of simulation calculations while ensuring a certain level of accuracy.

[0055] The target turbine, a specific, real wind turbine existing in the original wind farm equivalent model, has its current and voltage responses being the focus of subsequent analyses (such as protection setting verification and fault tracing). After the equivalent model is constructed, the target turbine is no longer explicitly included. However, by inversely estimating the boundary conditions, the terminal voltage and injected current of the target turbine under the same fault / disturbance can be estimated from the grid-connected electrical quantities of the equivalent model.

[0056] Back-calculation of boundary conditions refers to the process of using known electrical quantities at the grid connection point (such as voltage, total current injected into the grid, active / reactive power, etc.) and combining them with the structure and parameters of the equivalent model to inversely calculate the input conditions required for the electrical quantities at the generator terminals of a target unit. Specifically, back-calculation of boundary conditions may include the current grid connection point voltage. and the output current response of the target unit's equivalent group. Active current of the equivalence group reactive current of the equivalence group .

[0057] Current response refers to the process by which the current injected into the grid by the wind turbine changes over time under a specific disturbance (such as a grid fault or a sudden change in wind speed), and typically includes active current components and reactive current components.

[0058] Voltage response, under a specific disturbance, is the process by which the terminal voltage of a wind turbine changes over time, typically including the amplitude.

[0059] Specifically, the wind farm equivalent model is used to solve for the current and voltage responses of the target turbine based on the back-reasoned boundary conditions. This includes: simulating the wind farm equivalent model to obtain the back-reasoned boundary conditions of the target turbine; wherein the back-reasoned boundary conditions include: the current grid connection point voltage, the output current response, active current, and reactive current of the second turbine group to which the target turbine belongs; determining the back-reasoned calculation path of the target turbine based on the fault control mode corresponding to the second turbine group to which the target turbine belongs; and determining the current current and voltage responses of the target turbine based on the back-reasoned calculation path and the back-reasoned boundary conditions.

[0060] In the above-mentioned standardized equivalent modeling method for wind farms under fault conditions, the equivalent electrical distance from each of the multiple wind turbines to the grid connection point is obtained, and the positional differences of each turbine in the electrical topology are quantified, providing a physically meaningful clustering basis for subsequent grouping.

[0061] Based on the equivalent electrical distances, each wind turbine is first grouped to obtain the first unit group to which the wind turbine belongs. The dispersion of the equivalent electrical distances of multiple wind turbines in the first unit group satisfies the elbow screening condition with the number of groups in the first unit group. Firstly, the elbow screening condition automatically determines the optimal number of groups, avoiding subjective errors caused by manually setting the number of groups. Secondly, it ensures that the electrical distance dispersion of units within the same group is small (i.e., the impedance to the grid connection point is similar), thereby ensuring the voltage drop depth of units within the group during grid disturbances.

[0062] For each wind turbine in the first unit group, the wind turbines are grouped a second time based on the wind speed and fault steady-state terminal voltage of the wind turbines to obtain the second unit group to which the wind turbines belong. On the basis of similar electrical position, the differences in operating conditions (wind speed) and fault response characteristics (terminal voltage) are further distinguished, realizing dual fine grouping of position + state, which helps to improve the accuracy of transient simulation.

[0063] For each second unit group, an equivalent wind farm model is constructed based on the equivalent unit parameters and equivalent line parameters corresponding to the second unit group. Firstly, each second unit group is ultimately represented by an equivalent machine, significantly reducing the system order and simulation computational load. Secondly, the equivalent model simultaneously includes unit parameters (capacity, inertia, control parameters) and line parameters (equivalent impedance), accurately reproducing the power external characteristics from the units within the group to the grid connection point. Thirdly, the finer-grained grouping (two groupings) allows the equivalent model to maintain computational efficiency while achieving significantly higher accuracy than single-machine multiplication or single-grouping methods.

[0064] Among them, the wind farm equivalent model is used to solve the current and voltage responses of the target units by inferring the boundary conditions of the target units. On the one hand, when the electrical boundary conditions of the grid connection point are known, the current and voltage responses of any target unit inside can be inferred, which helps to find abnormal extreme values ​​in the simulation. On the other hand, it can quickly obtain the detailed response of a specific unit under fault or disturbance without modeling each unit separately, and is suitable for scenarios such as protection setting verification and fault source analysis.

[0065] In one embodiment, obtaining the equivalent electrical distance from each of the multiple wind turbine generators to the grid connection point includes: Determine the topology of each of the multiple wind turbine units; for wind turbine units with radial topology, determine the line path impedance between the wind turbine unit's access node and the grid connection point as the equivalent electrical distance between the wind turbine unit and the grid connection point; for wind turbine units with trunk topology, determine the accumulated value of the line impedance along the collector line topology path between the wind turbine unit's access node and the collector bus as the equivalent electrical distance between the wind turbine unit and the grid connection point.

[0066] The topology refers to the electrical connections between wind turbines within a wind farm, as well as between the turbines and the grid connection point. It describes the physical path and connection configuration of electrical energy from each turbine to the grid connection point.

[0067] like Figure 2 The radial wiring diagram shown represents a type of power collection wiring method for wind farms, in which multiple independent feeders (branches) radiate outward from the collection bus (or grid connection point), and each feeder connects several wind turbine units (WTG-1, WTG-2, WTG-M, and WTG-N).

[0068] like Figure 3 The trunk connection diagram shown represents a type of power collection connection method for wind farms, in which one or more turbines (WTG-1, WTG-2, WTG-M, and WTG-N) are connected in series on the same main line (trunk line). One end of the trunk line is connected to the collecting bus (or grid connection point), and multiple turbines (WTG-1, WTG-2, WTG-M, and WTG-N) are connected along the way through "T-connection" or "π-connection".

[0069] ; in, Let WTG-N be the equivalent electrical distance from the Nth wind turbine to the grid connection point. For the corresponding feeder line Line impedance, N This represents the number of line segments contained in the corresponding path.

[0070] After determining the topology of the wind turbine, the equivalent electrical distance for each wind turbine can be determined based on different topologies. Specifically, for wind turbines with a radial topology, the equivalent electrical distance from the wind turbine to the grid connection point is determined by the line path impedance between the wind turbine's access node and the grid connection point. For wind turbines with a trunk topology, the equivalent electrical distance from the wind turbine to the grid connection point is determined by the cumulative value of the line impedance along the collector line topology path from the wind turbine's access node to the collector bus.

[0071] In this embodiment, firstly, by adopting a two-step strategy of first identifying the topology type and then calculating the equivalent electrical distance separately, the scheme can be applied to wind farms with radial, trunk, and hybrid collector structures, thus having good engineering versatility. Secondly, it provides consistent and comparable numerical indicators for the first grouping, all of which are converted into impedance or accumulated impedance, avoiding the problem of clustering failure due to inconsistent indicator dimensions or physical meanings caused by different topologies.

[0072] In one embodiment, based on each equivalent electrical distance, the wind turbines are first grouped to obtain the first turbine group to which the wind turbines belong, including: Multiple candidate clustering schemes are obtained, and the number of clusters varies among the candidate clustering schemes. Based on each candidate grouping scheme, each wind turbine is pre-grouped to obtain the total electrical distance error within each category corresponding to each candidate grouping scheme. Based on the mapping relationship sequence between electrical distance error within the total category and the number of groups, the optimal number of groups is determined among the candidate grouping schemes; where the point of the optimal number of groups in the mapping relationship sequence is the maximum point of the absolute value of the second difference of the mapping relationship sequence. Based on the optimal number of groups and the equivalent electrical distances, the wind turbines are first grouped to obtain the first group of wind turbines.

[0073] The candidate clustering schemes represent the clustering strategies attempted to determine different group sizes k before finalizing the number of categories. Each candidate clustering scheme includes a specific k (e.g., 2, 3, 4...10) and the specific grouping results after pre-clustering all wind turbines according to that k value. This serves as the search space for finding the optimal number of groups. By traversing multiple candidate schemes (e.g., k from 2 to 10), the error index corresponding to each scheme is calculated, and the best k is selected.

[0074] The total electrical distance error within a category represents the squared difference between the equivalent electrical distance of each unit within each group and the center (mean) of that group, after allocating all wind turbines to k groups for a given candidate grouping scheme (fixed k value).

[0075] The mapping sequence represents the total intra-class electrical distance error with the number of groups k as the independent variable. As the dependent variable, it forms an ordered sequence arranged in ascending order of k.

[0076] The optimal number of groups represents the number of groups that achieve the best balance between model accuracy and model complexity. The optimal number of groups is defined as k corresponding to the maximum point of the absolute value of the second difference of the mapping sequence.

[0077] Specifically, a series of candidate clustering schemes (number of clusters) are set up, and clustering is performed sequentially using electrical distance as the clustering index and the k-means algorithm. For each candidate clustering scheme, the sum of squared within-cluster errors corresponding to the candidate clustering scheme is calculated. For example, let the number of clusters be... , No. Each subgroup contains Typhoon turbine, its internal first The electrical distances corresponding to the Taiwanese units are as follows: , Let represent the electrical distance center value of the k-th cluster. Then, the candidate clustering scheme has the following number of clusters: In the case of a single clustering, the total intra-class electrical distance error for: ; ; As the number of primary clusters increases, the electrical distance differences between units within each cluster gradually decrease, and the overall electrical distance error decreases accordingly. However, when the number of clusters increases to a certain extent, the downward trend of error gradually slows down, while the model complexity and computational scale continue to increase. Therefore, by analyzing the trend curve of the overall electrical distance error changing with the number of primary clusters, and based on the elbow principle, the optimal number of clusters is selected corresponding to the significant slowdown in the downward trend of error. This achieves a comprehensive balance between the ability to preserve the electrical characteristics within the wind farm and the computational complexity of the model. Finally, based on the equivalent electrical distance index of the units, the primary clustering of the entire wind farm is determined according to the optimal number of clusters. This primary clustering is only related to the wind farm topology and only needs to be performed once for a specific wind farm.

[0078] In this embodiment, firstly, by setting candidate schemes with different numbers of groups, a complete search space is constructed to avoid missing better grouping results due to a fixed number of groups. Secondly, by using the maximum absolute value of the second difference of the mapping relationship sequence as the criterion for the optimal number of groups, the selection of the number of groups is automated and mathematical, avoiding subjective errors caused by human experience in setting the number of groups.

[0079] In one embodiment, for each wind turbine in the first unit group, the wind turbines are further grouped a second time based on their wind speed and fault steady-state terminal voltage to obtain the second unit group to which the wind turbines belong. This includes: for each wind turbine in the first unit group, obtaining the fault steady-state voltage and wind speed of the wind turbine; determining the fault steady-state terminal voltage of the wind turbine according to the calculation path matched by the topology to which the wind turbine belongs and the fault steady-state voltage; and determining the second unit group to which the wind turbine belongs based on the fault steady-state terminal voltage and wind speed.

[0080] Among them, fault steady-state voltage represents the effective voltage value measured at the grid connection point of the wind turbine unit when the power system experiences a fault (such as a three-phase short circuit) and enters the steady-state stage (i.e., after the transient components have basically decayed during the fault duration).

[0081] Specifically, obtain the fault steady-state voltage Specifically, this can include: based on the voltage amplitude at the grid connection point at the moment of the fault. And the voltage rise at the grid connection point caused by reactive power support from wind farms. The calculation yields the following formula: ; for According to the fault impedance System-side impedance and infinite grid voltage amplitude The formula for calculating the voltage amplitude at the grid connection point at the instant of the fault is as follows: ; for Treating the entire wind farm as a single reactive current source, neglecting the on-site lines, and assuming that the terminal voltages of each turbine are equal, the total reactive power output is equal to the steady-state voltage at the grid connection point during faults. Relatedly, the power station calculates reactive power and voltage rise. The formula is as follows: ; ; ; in, N This refers to the number of wind turbine units in the wind farm. This refers to the reactive current of a single wind turbine unit. Let be the impedance from the grid connection point to the fault point. Based on the above formula, the fault steady-state voltage can be calculated. .

[0082] For example, for and ,like Figure 4 The diagram shows an external fault in a wind farm. The fault resistor, For system-side impedance, This is the impedance from the wind farm to the short-circuit point.

[0083] In this embodiment, firstly, the scope of the second grouping operation is limited to within each first unit group, avoiding cross-group mixed processing and ensuring the consistency of electrical position references during grouping. Secondly, different fault voltage calculation paths are matched according to radial or trunk topology, avoiding errors caused by uniform simplification of calculations and improving the accuracy of fault steady-state voltage calculation. Thirdly, by independently performing the second grouping within each first unit group, a hierarchical progressive clustering is formed: the first-level grouping ensures electrical position consistency; the second-level grouping ensures consistency of operating status and fault response. Overall, the final second unit group has high internal homogeneity and external distinguishability, forming a standardized aggregation modeling framework suitable for fixed topology wind farms. This significantly improves the model's standardization and engineering reusability, providing support for the engineering of standardized aggregation modeling of wind farms.

[0084] In one embodiment, the fault steady-state terminal voltage of the wind turbine is determined according to the calculation path matched to the topology of the wind turbine and the fault steady-state voltage, including: For wind turbines with radial topology, the fault steady-state terminal voltage of the wind turbine is determined based on the fault steady-state voltage, the turbine current, and the turbine voltage. For wind turbines with trunk topology, the fault steady-state voltage is used as the initial value of the terminal voltage. The forward-backward substitution method in power flow calculation is used to calculate the fault steady-state terminal voltage of each wind turbine on the feeder.

[0085] Specifically, for wind turbines in a radial topology, since each turbine connects to the grid via an independent path and there is no feeder-to-line stacking, forward-backward calculation is unnecessary. For each wind turbine, the current fault steady-state voltage is considered. The fault steady-state terminal voltage of the corresponding unit can be directly calculated from the voltage-current relationship of the wind turbine itself and the line impedance between the wind turbine and the grid connection point. The voltage-current relationship is as follows: ; ; ; ; ; in, , These are reference values ​​for the active and reactive current output of the wind turbine. and This refers to the rated voltage and current of the wind turbine. The maximum allowable current for the converter. To provide the upper limit of active current that the converter is allowed to pass after reactive power support, This is the reference value of active current obtained from DC voltage control during the fault period. This represents the active current during normal steady-state operation before the fault. This represents the active power output from the grid side before the fault. This is the grid voltage. Let be the wind speed. Before the fault, the active power output of the unit is determined by the wind speed, which can be expressed as a function of the wind speed.

[0086] Specifically, for dry-type topology power stations, the calculated fault steady-state voltage will be... As the initial value of the terminal voltage, the forward-backward substitution method in power flow calculation is used to calculate the fault steady-state terminal voltage of each wind turbine on the feeder. The specific steps are as follows: (1) Initialization and power calculation: The initial value of the terminal voltage of all wind turbines in the wind farm is set to According to the above-mentioned voltage and current relationship of the wind turbine, the active current and reactive current of each unit are calculated, and then the complex power of each unit is obtained; (2) Forward calculation of feeder current and voltage drop: According to the wind farm topology, starting from the farthest unit on the grid side of each feeder, the current on the feeder is calculated using the current of each unit, and then the voltage drop on the line is calculated; (3) Backward correction of node voltage: Starting from the grid connection point, the corrected terminal voltage of each wind turbine is obtained according to the voltage drop on the line calculated in step (2); (4) Iterative convergence: Compare the terminal voltage values ​​before and after correction. If the preset convergence accuracy is not met, the corrected voltage value is used as the new initial value of the unit. Repeat the above power calculation, forward and backward process until the terminal voltage calculation of all wind turbines converges, and the fault steady-state terminal voltage of each unit can be obtained.

[0087] In this embodiment, firstly, considering the characteristics of radial structures where each feeder is independent and branch impedances are uncoupled, a direct calculation method based on local electrical quantities (fault steady-state voltage, unit current, and unit voltage) is adopted, avoiding unnecessary global iterations and achieving high computational efficiency. Secondly, considering the characteristics of trunk-type structures where units are connected in series on the same main line and electrical distances increase from near to far, a forward-backward substitution method is used, which can accurately account for the cumulative effect of the current of each unit along the line on the voltage drop of the upstream line. Thirdly, by matching differentiated calculation methods according to topology structure—direct calculation for radial structures and forward-backward substitution for trunk structures—accurate characterization of the fault steady-state voltage distribution law under two typical collector line structures is achieved, avoiding errors caused by uniform simplification calculations.

[0088] In one embodiment, the wind farm equivalent model is used to solve for the current and voltage responses of the target turbine by inferring the boundary conditions from the target turbine, including: The back-reasoned boundary conditions of the target unit are obtained by simulating the equivalent model of the wind farm. The back-reasoned boundary conditions include: the grid connection point voltage at the current moment, the output current response of the second unit group to which the target unit belongs, the active current and the reactive current. Based on the fault control mode of the second unit group to which the target unit belongs, the back-calculation path of the target unit is determined. Based on the back-calculation path and back-calculation boundary conditions, the current response and voltage response of the target unit at the current moment are determined.

[0089] The inverse boundary conditions include: the current grid connection point voltage. Output current response of the second unit group to which the target unit belongs Active current of the second unit group to which the target unit belongs The reactive current of the second unit group to which the target unit belongs .

[0090] Fault control mode refers to a special operating state and corresponding set of control logic that a wind turbine (or its converter) switches to when it detects an abnormal grid voltage (drop or surge), according to grid connection guidelines or manufacturer strategies. It determines the active / reactive current output characteristics of the unit during fault periods and recovery periods.

[0091] Specifically, the fault control modes include a first control mode, a second control mode, a third control mode, and a fourth control mode. In the first control mode, the wind turbine enters a reactive power support priority control mode. The reactive current is determined by a national standard formula. During the fault, the wind turbine continues to maintain DC voltage control, and the direct-drive wind turbine can normally deliver active power. The DC voltage can remain stable, although short-term oscillations may occur at the initial stage of the fault and after the fault is cleared. In the second control mode, the wind turbine enters a reactive power support priority control mode. The reactive current is determined by a national standard formula. During the fault, the active current is determined by the reactive current and the inverter capacity. The active power output in the fault steady-state is less than the pre-fault steady-state value. After the fault is cleared, the active power will also return to near the pre-fault steady-state value the moment the voltage recovers. The third control mode indicates that the wind turbine enters a reactive power support priority control mode. The reactive current is determined by the national standard formula. During a fault, the active current is also determined by the reactive current and the inverter capacity. The active power output in the fault steady state is less than the steady state value before the fault. However, after the fault is cleared, the active power is still lower than the steady state value before the fault when the voltage recovers. It takes a period of time to recover to the steady state value before the fault. The fourth control mode indicates the control mode when the reactive current maintains normal operation. The wind turbine often uses unity power factor control, that is, the reactive current control reference value is 0. The active current also maintains DC voltage control, and the response is the same as the first control mode.

[0092] The reverse calculation path refers to the electrical links and corresponding calculation sequence through which the target unit's terminal voltage and injected current are calculated in reverse from the known reverse boundary conditions (such as grid connection point voltage, equivalent generator output current, etc.) in the wind farm equivalent model.

[0093] Specifically, the back-calculated boundary conditions of the target unit are obtained by simulating the equivalent model of the wind farm; among which, the back-calculated boundary conditions include: the current grid connection point voltage. Output current response of the second unit group to which the target unit belongs Active current of the second unit group to which the target unit belongs The reactive current of the second unit group to which the target unit belongs .

[0094] Based on the fault control mode corresponding to the second unit group to which the target unit belongs, the back-calculation path of the target unit is determined; based on the back-calculation path and back-calculation boundary conditions, the current response and voltage response of the target unit at the current moment are determined, specifically including: If the fault control mode corresponding to the target unit is the first control mode, i.e., the operating mode when reactive power support is prioritized and DC voltage control is maintained, then the reactive current of the second unit group will be equally distributed as the reactive current of the target unit. Based on the proportion of the target unit's active power output to the total active power output of the group before the fault, the active current of the second unit group will be allocated to obtain the current active (and reactive) current response of the target unit. , .

[0095] If the target unit's fault control mode is the second or third control mode, i.e., a mode where reactive power support is prioritized and active power transmission is limited by inverter capacity, then the reactive current of the second unit group will be equally distributed as the reactive current of the target unit. The active (reactive) current response of the target unit at the current moment will be calculated based on the inverter current limiting constraint of the target unit. , .

[0096] If the target unit's fault control mode is the fourth control mode, i.e., the operation mode maintaining unity power factor control and DC voltage control, then the total current of the second unit group is proportionally allocated based on the target unit's active power output before the fault, thus obtaining the target unit's current total current response. .

[0097] Obtain the current output current of the target unit at the current moment. Then, combined with the current grid connection point voltage... and the equivalent line impedance of the target unit Calculate the terminal voltage of the target unit at the current moment. And further obtain the voltage response of the target unit. By repeating the above process at each simulation moment during the fault process, the collaborative calculation of the external characteristics of the wind farm and the response of the specified unit can be achieved; In this embodiment, firstly, simulation is performed based on an equivalent model (rather than the original detailed model), resulting in high computational efficiency and the ability to quickly obtain key boundary quantities such as grid connection point voltage and equivalent generator output current. Secondly, the corresponding reverse calculation path is selected according to the fault control mode (such as low-voltage ride-through reactive power priority mode), ensuring that the reverse calculation follows the actual control logic of the unit and avoiding errors caused by path mismatch. Thirdly, it achieves a reverse mapping from macroscopic electrical quantities at the grid connection point to the microscopic response of an internal single unit, allowing the acquisition of the target unit's terminal voltage and injected current without the need for separate simulation of a detailed model.

[0098] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0099] Based on the same inventive concept, this application also provides a fault-prone wind farm standardized equivalent modeling device for implementing the above-mentioned fault-prone wind farm standardized equivalent modeling method. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of one or more fault-prone wind farm standardized equivalent modeling device embodiments provided below can be found in the limitations of the fault-prone wind farm standardized equivalent modeling method described above, and will not be repeated here.

[0100] In one embodiment, such as Figure 5 As shown, a standardized equivalent modeling device for wind farms under fault conditions is provided, wherein: The acquisition module 501 is used to acquire the equivalent electrical distance from each of the multiple wind turbine units to the grid connection point; The first grouping module 502 is used to perform the first grouping of each wind turbine based on each equivalent electrical distance to obtain the first unit group to which the wind turbine belongs; wherein, the dispersion of the equivalent electrical distances of multiple wind turbines in the first unit group satisfies the elbow screening condition with respect to the number of groups in the first unit group. The secondary grouping module 503 is used to perform a second grouping of the wind turbines in each first unit group based on the wind speed and fault steady-state terminal voltage of the wind turbines, so as to obtain the second unit group to which the wind turbines belong. Modeling module 504 is used to construct an equivalent wind farm model for each second unit group based on the equivalent unit parameters and equivalent line parameters corresponding to the second unit group; wherein, the equivalent wind farm model is used to solve the current response and voltage response of the target unit by back-deriving the boundary conditions of the target unit.

[0101] Each module in the aforementioned standardized equivalent modeling device for wind farms under fault conditions can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the computer device's memory as software, so that the processor can call and execute the corresponding operations of each module.

[0102] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 6 As shown, this computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores data such as equivalent electrical distance. The I / O interfaces are used for information exchange between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When executed by the processor, the computer program implements a standardized equivalent modeling method for wind farms under fault conditions.

[0103] Those skilled in the art will understand that Figure 6 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0104] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the above-described method steps.

[0105] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the above-described method steps.

[0106] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the above-described method steps.

[0107] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0108] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0109] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A standardized equivalent modeling method for wind farm under fault conditions, characterized in that, The method includes: Obtain the equivalent electrical distance from each of the multiple wind turbine units to the grid connection point; Based on the equivalent electrical distances, the wind turbines are first grouped to obtain the first turbine group to which the wind turbines belong; wherein, the dispersion of the equivalent electrical distances of the multiple wind turbines in the first turbine group satisfies the elbow screening condition with respect to the number of groups in the first turbine group. For each wind turbine in the first unit group, the wind turbine is further divided into second groups based on the wind speed and fault steady-state terminal voltage of the wind turbine to obtain the second unit group to which the wind turbine belongs. For each of the second unit groups, an equivalent wind farm model is constructed based on the equivalent unit parameters and equivalent line parameters corresponding to the second unit group; wherein, the equivalent wind farm model is used to solve the current response and voltage response of the target unit by inferring the boundary conditions of the target unit.

2. The method according to claim 1, characterized in that, The process of obtaining the equivalent electrical distance from each of the multiple wind turbine generators to the grid connection point includes: Determine the topology to which each of the multiple wind turbine units belongs; For wind turbines with a radial topology, the line path impedance between the wind turbine's access node and the grid connection point is determined as the equivalent electrical distance between the wind turbine and the grid connection point. For wind turbines with trunk-type topology, the accumulated line impedance along the collector line topology path from the wind turbine's access node to the collector bus is determined as the equivalent electrical distance from the wind turbine to the grid connection point.

3. The method according to claim 1, characterized in that, Based on the equivalent electrical distance, the wind turbines are first grouped to obtain the first turbine group to which the wind turbines belong, including: Multiple candidate clustering schemes are obtained, and the number of clusters varies among the candidate clustering schemes. Based on each of the candidate grouping schemes, each of the wind turbine units is pre-grouped to obtain the total intra-class electrical distance error corresponding to each of the candidate grouping schemes. Based on the mapping relationship sequence between the total electrical distance error and the number of groups, the optimal number of groups is determined among each candidate grouping scheme; wherein, the point of the optimal number of groups in the mapping relationship sequence is the maximum point of the absolute value of the second difference of the mapping relationship sequence; Based on the optimal number of groups and the equivalent electrical distances, the wind turbines are first grouped to obtain the first group of turbines to which the wind turbines belong.

4. The method according to claim 1, characterized in that, For each wind turbine in the first unit group, based on the wind speed and fault steady-state terminal voltage of the wind turbine, the wind turbine is further divided into a second group to obtain the second unit group to which the wind turbine belongs, including: For each wind turbine in the first unit group, obtain the fault steady-state voltage and wind speed of the wind turbine; The fault steady-state terminal voltage of the wind turbine is determined according to the calculation path matched by the topology to which the wind turbine belongs and the fault steady-state voltage. Based on the fault steady-state terminal voltage and the wind speed, the second unit group to which the wind turbine belongs is determined.

5. The method according to claim 4, characterized in that, The step of determining the fault steady-state terminal voltage of the wind turbine according to the calculation path matched to the topology of the wind turbine and the fault steady-state voltage includes: For wind turbines with a radial topology, the fault steady-state terminal voltage of the wind turbine is determined based on the fault steady-state voltage, the turbine current, and the turbine voltage. For wind turbines with trunk topology, the fault steady-state voltage is used as the initial value of the terminal voltage. The forward-backward substitution method in power flow calculation is used to calculate the fault steady-state terminal voltage of each wind turbine on the feeder.

6. The method according to claim 1, characterized in that, The equivalent model of the wind farm is used to solve for the current and voltage responses of the target turbine based on the back-calculation of boundary conditions, including: The back-reasoned boundary conditions of the target unit are obtained by simulating the equivalent model of the wind farm; wherein, the back-reasoned boundary conditions include: the grid connection point voltage at the current moment, the output current response of the second unit group to which the target unit belongs, the active current and the reactive current; Based on the fault control mode of the second unit group to which the target unit belongs, the reverse calculation path of the target unit is determined. Based on the back-calculation path and the back-calculation boundary conditions, the current response and voltage response of the target unit at the current moment are determined.

7. A standardized equivalent modeling device for wind farms under fault conditions, characterized in that, The device includes: The acquisition module is used to obtain the equivalent electrical distance from each of the multiple wind turbine units to the grid connection point; A primary grouping module is used to perform a first grouping of each wind turbine based on the equivalent electrical distance, to obtain a first unit group to which the wind turbine belongs; wherein, the dispersion of the equivalent electrical distances of multiple wind turbines in the first unit group satisfies the elbow screening condition with respect to the number of groups in the first unit group. The secondary grouping module is used to perform a second grouping of the wind turbines in each of the first unit groups based on the wind speed and fault steady-state terminal voltage of the wind turbines, so as to obtain the second unit group to which the wind turbines belong. The modeling module is used to construct an equivalent wind farm model for each of the second unit groups based on the equivalent unit parameters and equivalent line parameters corresponding to the second unit group; wherein, the equivalent wind farm model is used to solve the current response and voltage response of the target unit by back-inferring the boundary conditions of the target unit.

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