A photovoltaic power station equivalent modeling method and device for electromagnetic transient simulation

Abstract

The application discloses a photovoltaic power station equivalent modeling method and device for electromagnetic transient simulation, and belongs to the technical field of photovoltaic power station simulation modeling, specifically: a topology model of a target photovoltaic power station is acquired, and each photovoltaic power generation unit in the topology model is clustered to obtain a first equivalent model; a fault working condition is set at a grid-connected point of the first equivalent model and simulation analysis is performed to obtain fault response characteristic data of each equivalent photovoltaic power generation unit in the first equivalent model, and each equivalent photovoltaic power generation unit is clustered to obtain a plurality of clusters; equivalent parameters of the target photovoltaic power station are calculated, and the topology model is converted into a second equivalent model; output data of the topology model and the second equivalent model under the same simulation working condition are compared, and if a comparison result satisfies a preset condition, the second equivalent model is taken as an equivalent model of the target photovoltaic power station. Therefore, by implementing the application, electromagnetic transient simulation precision of the equivalent model can be improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power plant simulation modeling technology, and in particular to an equivalent modeling method and apparatus for photovoltaic power plants oriented towards electromagnetic transient simulation. Background Technology

[0002] As the installed capacity of large-scale photovoltaic (PV) power plants continues to increase, a single large PV power plant often contains dozens or even hundreds of PV power generation units. When conducting grid-connected electromagnetic transient simulations of PV power plants, modeling each and every power generation unit in detail would result in a massive simulation model, a sharp increase in computational load, and a significant decrease in simulation speed, making it difficult to meet the practical needs of rapid dynamic behavior analysis of PV power plants in engineering. Therefore, engineering typically employs equivalent modeling methods, clustering PV power generation units with similar characteristics within the PV power plant to establish a simplified equivalent model capable of reproducing the dynamic behavior of the PV power plant, thus reducing the number of simulation units while maintaining simulation accuracy.

[0003] Existing equivalent modeling methods for photovoltaic (PV) power plants often rely on simple merging based on the consistency of component parameters, failing to adequately consider the differences in the response characteristics of PV power generation units under fault conditions. This results in equivalent models that cannot accurately reproduce the dynamic behavior of PV power plants during fault ride-through, leading to insufficient simulation accuracy. Furthermore, for key supporting components within PV power plants, such as box-type transformers and collector lines, existing methods do not perform case-specific equivalent parameter calculations based on the characteristics of clustering, thus requiring improvement in the rationality and accuracy of the equivalent process. In addition, current equivalent modeling processes generally lack standardized model validity verification steps, making it impossible to comprehensively assess the consistency between the equivalent model and the detailed model under steady-state and transient conditions, thus compromising the reliability of the equivalent model. Summary of the Invention

[0004] This invention provides a method and apparatus for equivalent modeling of photovoltaic power plants for electromagnetic transient simulation. It can perform equivalent modeling based on the dynamic behavior of photovoltaic power plants during fault ride-through, thereby improving the accuracy of electromagnetic transient simulation of the equivalent model.

[0005] This invention provides an equivalent modeling method for photovoltaic power plants for electromagnetic transient simulation, including: Obtain the topology model of the target photovoltaic power station, and based on the photovoltaic inverter model, cluster the photovoltaic power generation units under each collector line in the topology model to obtain the first equivalent model; A fault condition is set at the grid connection point of the first equivalent model and simulation analysis is performed to obtain fault response characteristic data of each equivalent photovoltaic power generation unit in the first equivalent model. Based on the fault response characteristic data, each equivalent photovoltaic power generation unit is clustered to obtain multiple clusters. The equivalent parameters of the target photovoltaic power station are calculated, and based on each cluster and each equivalent parameter, the topology model is converted into a second equivalent model; wherein, the equivalent parameters include equivalent photovoltaic power generation unit parameters, equivalent transformer parameters, and equivalent collection line parameters; The output data of the topology model and the second equivalent model under the same simulation conditions are compared. If the comparison result meets the preset conditions, the second equivalent model is used as the equivalent model of the target photovoltaic power station.

[0006] This invention, through obtaining a topology model and clustering photovoltaic power generation units based on photovoltaic inverter models, can initially compress the model size according to the inherent attributes of the equipment, obtaining a first equivalent model for subsequent simulation. By setting fault conditions at the grid connection point of the first equivalent model and obtaining fault response characteristic data of each equivalent photovoltaic power generation unit, and then performing secondary clustering on each equivalent photovoltaic power generation unit accordingly, the clustering results can reflect the dynamic behavior differences of each photovoltaic power generation unit during the fault transient process, ensuring that photovoltaic power generation units within the same cluster respond consistently under grid disturbances. By calculating equivalent parameters including equivalent photovoltaic power generation unit parameters, equivalent transformer parameters, and equivalent collector line parameters, and converting the topology model into a second equivalent model accordingly, the electrical structure of the equivalent model can be made equivalent to the topology model while reducing the number of simulation units. By comparing and verifying the output data of the topology model and the second equivalent model under the same operating conditions, the deviation of the equivalent model can be quantitatively assessed, ensuring that the final output equivalent model has reliable simulation accuracy. Compared to existing technologies that fail to adequately consider the differences in fault response characteristics, resulting in insufficient accuracy of transient simulation, this application can perform equivalent modeling based on the dynamic behavior of photovoltaic power plants during fault ride-through, thereby improving the electromagnetic transient simulation accuracy of the equivalent model.

[0007] Furthermore, obtaining the topology model of the target photovoltaic power station includes: The constituent components of the target photovoltaic power station are determined; wherein, the constituent components include photovoltaic power generation units, box-type transformers, collector lines, main transformers and reactive power compensation equipment, the photovoltaic power generation units include photovoltaic inverters, photovoltaic arrays and filters, the collector lines connect the photovoltaic power generation units and the box-type transformers, and one photovoltaic power generation unit corresponds to one box-type transformer; Based on the electrical wiring relationship of the target photovoltaic power station, the constituent components are connected to obtain a topology model.

[0008] The embodiments of the present invention determine the components of a photovoltaic power station and the electrical wiring relationships between the components, and construct a topology model accordingly, which can provide a modeling benchmark for subsequent clustering and equivalent parameter calculation.

[0009] Furthermore, based on the photovoltaic inverter model, the photovoltaic power generation units under each collector line in the topology model are clustered to obtain a first equivalent model, including: Photovoltaic power generation units with the same photovoltaic inverter model under the same collector line within the topology model are grouped together to obtain multiple first clusters; Each photovoltaic power generation unit in each of the first clusters is equivalent to an equivalent photovoltaic power generation unit, and the topology model is converted into a first equivalent model based on each of the equivalent photovoltaic power generation units.

[0010] This invention, by grouping photovoltaic power generation units with the same model of photovoltaic inverter under the same collector line into a group and equating each group with an equivalent photovoltaic power generation unit, can initially compress the detailed topology model into a controllable alternative equivalent model, thereby reducing the number of calculation objects in subsequent fault simulation.

[0011] Furthermore, the step of setting up fault conditions at the grid connection point of the first equivalent model and performing simulation analysis to obtain fault response characteristic data of each equivalent photovoltaic power generation unit within the first equivalent model includes: The equivalent photovoltaic power generation units in the first equivalent model are set to operate at rated power. Multiple fault types are set at the grid connection point of the first equivalent model, and electromagnetic transient simulation calculations are performed under each fault type according to the preset voltage drop specifications to obtain the fault response curves of each equivalent photovoltaic power generation unit under each fault type. The aforementioned fault response curves are used as fault response characteristic data.

[0012] The embodiments of the present invention can obtain the response curves of each equivalent photovoltaic power generation unit under various fault types by setting the rated power state, setting multiple fault types at the grid connection point, and performing electromagnetic transient simulation according to the preset voltage drop specifications, thereby providing data support for subsequent secondary clustering based on fault response characteristics.

[0013] Furthermore, based on the fault response characteristic data of each of the aforementioned units, clustering is performed on each of the equivalent photovoltaic power generation units to obtain multiple clusters, including: Based on the similarity between the fault response curves of each equivalent photovoltaic power generation unit, the equivalent photovoltaic power generation units are clustered to obtain multiple clusters; wherein, the similarity is determined according to the shape of the fault response curve, voltage drop depth, power peak, steady-state value and recovery time.

[0014] This invention, through clustering based on the similarity of the fault response curves of each equivalent photovoltaic power generation unit, can group equivalent photovoltaic power generation units with similar dynamic behaviors into the same cluster, enabling the equivalent model to accurately reproduce the dynamic response of the photovoltaic power station during fault ride-through.

[0015] Furthermore, the calculation of the equivalent parameters of the target photovoltaic power station includes: For any cluster, the active power, reactive power and apparent power of all photovoltaic power generation units in the cluster are superimposed to obtain the equivalent active power, equivalent reactive power and the first equivalent apparent power. The equivalent active power, the equivalent reactive power and the first equivalent apparent power are used as the equivalent photovoltaic power generation unit parameters corresponding to the cluster. The apparent power of the box transformers corresponding to each photovoltaic power generation unit in the cluster is superimposed to obtain the second equivalent apparent power, and the impedance of each box transformer is equalized to obtain the first equivalent impedance. The second equivalent apparent power and the first equivalent impedance are used as the equivalent box transformer parameters corresponding to the cluster. For any collector line, based on the impedance and current of each segment of the collector line, each segment is made into a second equivalent impedance of the collector line. Based on the second equivalent impedance and current of each collector line, the collector lines are combined in parallel to obtain a third equivalent impedance. The third equivalent impedance is used as the parameter of the equivalent collector line.

[0016] By calculating the equivalent power generation unit parameters, equivalent transformer parameters, and equivalent collector line parameters, this invention can ensure that the total power transmission capacity and impedance characteristics of each component are matched before and after equivalence, making the equivalent model and the topology model equivalent in electrical performance.

[0017] Further, the step of equating the impedances of each of the box-type transformers to obtain the first equivalent impedance includes: When the impedance of each of the box-type transformers is the same, the first equivalent impedance is obtained by dividing the impedance by the number of each of the box-type transformers. When the impedances of the various box-type transformers are different, the first equivalent impedance is calculated under the condition that the total power loss of the cluster before and after the equivalent impedance is equal.

[0018] By distinguishing between cases where the transformer substation impedance is the same and cases where it is different, and calculating the equivalent impedance separately, the impedance parameters of the equivalent transformer substation can accurately match the actual loss characteristics of the original cluster under different engineering configurations, thus avoiding parameter deviations caused by using a single calculation method.

[0019] Further, the step of converting the topology model into a second equivalent model based on each of the clusters and each of the equivalent parameters includes: Based on each cluster, determine the photovoltaic power generation units, box transformers, and collection lines that need to be converted in the topology model; Based on the equivalent parameters, the photovoltaic power generation units, box-type transformers and collector lines that need to be converted are respectively converted into equivalent photovoltaic power generation units, equivalent box-type transformers and equivalent collector lines; Based on the electrical wiring relationships of the topology model, the converted equivalent photovoltaic power generation unit, equivalent transformer and equivalent collector line are connected to the main transformer and reactive power compensation equipment of the topology model to obtain the second equivalent model.

[0020] This invention determines the components to be converted based on cluster division, converts them into corresponding equivalent components according to equivalent parameters, and then connects the equivalent components to the retained main transformer and reactive power compensation equipment according to the electrical wiring relationship of the original topology. This simplifies the model scale while fully preserving the interface characteristics between the photovoltaic power station and the external power grid, as well as the control response capabilities of key equipment within the station.

[0021] Furthermore, after comparing the output data of the topological model and the second equivalent model under the same simulation conditions, the method further includes: If the comparison result does not meet the preset conditions, the source of the deviation is determined based on the deviation characteristics of the output data. When the judgment bias originates from clustering, clustering is re-executed; when the judgment error originates from the calculation of equivalent parameters, the equivalent parameters are recalculated until the adjusted comparison results meet the preset conditions.

[0022] This invention, through determining the source of deviations that do not meet preset conditions, and accordingly selecting to re-cluster or recalculate equivalent parameters until the requirements are met, can pinpoint the root cause of errors in the equivalent model, thereby avoiding blind adjustments and achieving model accuracy optimization with the fewest iterations.

[0023] Another embodiment of the present invention provides an equivalent modeling device for photovoltaic power plants for electromagnetic transient simulation, comprising: a first clustering module, a second clustering module, an equivalent parameter calculation module, and a simulation verification module; The first clustering module is used to obtain the topology model of the target photovoltaic power station, and based on the photovoltaic inverter model, to cluster the photovoltaic power generation units under each collector line in the topology model to obtain the first equivalent model. The second clustering module is used to set up fault conditions at the grid connection point of the first equivalent model and perform simulation analysis to obtain fault response characteristic data of each equivalent photovoltaic power generation unit in the first equivalent model, and to cluster each equivalent photovoltaic power generation unit based on the fault response characteristic data to obtain multiple clusters. The equivalent parameter calculation module is used to calculate the equivalent parameters of the target photovoltaic power station, and based on each cluster and each equivalent parameter, convert the topology model into a second equivalent model; wherein, the equivalent parameters include equivalent photovoltaic power generation unit parameters, equivalent transformer parameters, and equivalent collection line parameters; The simulation verification module is used to compare the output data of the topology model and the second equivalent model under the same simulation conditions. If the comparison result meets the preset conditions, the second equivalent model is used as the equivalent model of the target photovoltaic power station. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating an embodiment of the photovoltaic power plant equivalent modeling method for electromagnetic transient simulation provided by the present invention. Figure 2 A schematic diagram of the structure of one embodiment of a photovoltaic power station provided by the present invention; Figure 3 A schematic diagram of a current collection line according to an embodiment of the present invention; Figure 4 A schematic diagram of the structure of an embodiment of the photovoltaic power generation unit provided by the present invention; Figure 5 A schematic diagram of the structure of an embodiment of the equivalent photovoltaic power generation unit provided by the present invention; Figure 6 A schematic diagram of a structure of an embodiment of a parallel photovoltaic generator set provided by the present invention; Figure 7 A schematic diagram of the structure of one embodiment of the photovoltaic power plant equivalent model provided by the present invention; Figure 8 This is a schematic diagram of an embodiment of the photovoltaic power plant equivalent modeling device for electromagnetic transient simulation provided by the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0027] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0030] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0031] See Figure 1 To address the problem of insufficient transient simulation accuracy caused by existing technologies failing to fully consider differences in fault response characteristics, an embodiment of the present invention provides an equivalent modeling method for photovoltaic power plants for electromagnetic transient simulation, including steps S101 to S104: Step S101: Obtain the topology model of the target photovoltaic power station, and based on the photovoltaic inverter model, cluster the photovoltaic power generation units under each collector line in the topology model to obtain the first equivalent model.

[0032] It should be noted that obtaining the topology model of the target photovoltaic power station and clustering the photovoltaic power generation units under each collector line within the topology model based on the photovoltaic inverter model to obtain the first equivalent model means that after obtaining the topology model of the target photovoltaic power station, each collector line is used as a grouping unit, and photovoltaic power generation units under the same collector line with the same photovoltaic inverter model are grouped into the same group. The photovoltaic power generation units within each group are completely identical in equipment structure and control parameters. Therefore, all photovoltaic power generation units within the group can be equivalent to one equivalent photovoltaic power generation unit, thereby initially compressing the topology model containing a large number of photovoltaic power generation units into a first equivalent model with a significantly reduced scale. The first equivalent model serves as an intermediate transitional model for subsequent fault simulation and secondary clustering analysis.

[0033] Preferably, obtaining the topology model of the target photovoltaic power station includes: The constituent components of the target photovoltaic power station are determined; wherein, the constituent components include photovoltaic power generation units, box-type transformers, collector lines, main transformers and reactive power compensation equipment, the photovoltaic power generation units include photovoltaic inverters, photovoltaic arrays and filters, the collector lines connect the photovoltaic power generation units and the box-type transformers, and one photovoltaic power generation unit corresponds to one box-type transformer; Based on the electrical wiring relationship of the target photovoltaic power station, the constituent components are connected to obtain a topology model.

[0034] In one embodiment, the topology of the photovoltaic power station is as follows: Figure 2 As shown, its components include transformers, reactive power compensation equipment, photovoltaic (PV) power generation units, and collector lines. The transformers include the main transformer and the transformers connected to the PV power generation units (i.e., box-type transformers). The PV power generation unit is the smallest PV power generation system in a PV power plant, including core components such as PV inverters, PV arrays, and filters. The collector lines consist of multiple lines, multiple PV power generation units, and multiple box-type transformers, with its topology as shown in the diagram. Figure 3 As shown. In particular, if a low-voltage reactive power compensation device is configured for a photovoltaic power station, a corresponding step-up transformer is also required; if a high-voltage direct-connect reactive power compensation device is configured, it can be directly connected to the photovoltaic power station without the need for an additional transformer. Reactive power compensation devices are mainly divided into static var compensators (SVCs) and static var generators (SVGs). Since SVGs are superior to SVCs in terms of response speed, low voltage characteristics, operational safety performance, harmonic characteristics, and economy, SVG models are usually selected in modeling and simulation.

[0035] Furthermore, the components of a photovoltaic power station can be constructed in electromagnetic transient simulation software. Based on the actual electrical wiring relationships of the photovoltaic power station, all photovoltaic power generation units, each section of collector lines, SVG reactive power compensation equipment, and all transformers within the station are connected sequentially to obtain the topology model of the photovoltaic power station. In particular, in the electromagnetic transient simulation software, the SVG model is a conventional model, which is generally set to operate in voltage control mode during normal operation and fault ride-through, with the control target being the grid connection voltage of the photovoltaic power station.

[0036] Preferably, the step of clustering photovoltaic power generation units under each collector line in the topology model based on the photovoltaic inverter model to obtain a first equivalent model includes: Photovoltaic power generation units with the same photovoltaic inverter model under the same collector line within the topology model are grouped together to obtain multiple first clusters; Each photovoltaic power generation unit in each of the first clusters is equivalent to an equivalent photovoltaic power generation unit, and the topology model is converted into a first equivalent model based on each of the equivalent photovoltaic power generation units.

[0037] In one embodiment, based on the differences in photovoltaic inverter models under each collector line, the photovoltaic power generation units corresponding to all collector lines within the photovoltaic power station are initially grouped. Photovoltaic power generation units with the same inverter model under the same collector line are grouped together, and each group of photovoltaic power generation units is equivalent to one equivalent photovoltaic power generation unit, resulting in the first equivalent model of the photovoltaic power station. Specifically, the photovoltaic inverter models under the same collector line are usually the same; it is generally assumed that photovoltaic inverters of the same model have completely identical structures and parameters, and can be classified into the same cluster. Before performing cluster analysis, based on the different photovoltaic inverter models under each collector line, all collector lines can be initially grouped, and they can be equivalent to several equivalent photovoltaic power generation units. The model obtained at this time is called the first equivalent model. Then, simulation calculations are performed on the first equivalent model to study and analyze the fault operation characteristics of each equivalent photovoltaic power generation unit. The convergence of fault response characteristics is used as a grouping index, and then the first equivalent model is further clustered.

[0038] Step S102: Set up fault conditions at the grid connection point of the first equivalent model and perform simulation analysis to obtain fault response characteristic data of each equivalent photovoltaic power generation unit in the first equivalent model. Based on the fault response characteristic data, cluster each equivalent photovoltaic power generation unit to obtain multiple clusters.

[0039] It should be noted that setting up fault conditions at the grid connection point of the first equivalent model and performing simulation analysis to obtain fault response characteristic data of each equivalent photovoltaic power generation unit within the first equivalent model, and clustering each equivalent photovoltaic power generation unit based on the fault response characteristic data to obtain multiple clusters means: using the first equivalent model as the simulation object, setting up multiple fault types at the grid connection point of the first equivalent model and performing electromagnetic transient simulation calculations according to preset voltage drop specifications, extracting the active power and reactive power response curves of each equivalent photovoltaic power generation unit during the fault period, as the fault response characteristic data of each equivalent photovoltaic power generation unit. On this basis, using the convergence of fault response characteristics of each equivalent photovoltaic power generation unit as the clustering index, comparing the similarity of the response curves of each equivalent photovoltaic power generation unit in dimensions such as shape, voltage drop depth, peak power, steady-state value, and recovery time, and grouping equivalent photovoltaic power generation units with highly similar dynamic behaviors into the same cluster, thus obtaining multiple clusters. This step expands the clustering criteria from equipment model to transient response characteristics, ensuring that units within the same cluster respond consistently under power grid disturbances, thereby guaranteeing the simulation accuracy of the final equivalent model under fault conditions.

[0040] Preferably, the step of setting up fault conditions at the grid connection point of the first equivalent model and performing simulation analysis to obtain fault response characteristic data of each equivalent photovoltaic power generation unit within the first equivalent model includes: The equivalent photovoltaic power generation units in the first equivalent model are set to operate at rated power. Multiple fault types are set at the grid connection point of the first equivalent model, and electromagnetic transient simulation calculations are performed under each fault type according to the preset voltage drop specifications to obtain the fault response curves of each equivalent photovoltaic power generation unit under each fault type. The aforementioned fault response curves are used as fault response characteristic data.

[0041] In one embodiment, four fault conditions are set for the grid connection point: three-phase short circuit, two-phase ground short circuit, two-phase phase-to-phase short circuit, and single-phase ground short circuit. The voltage drop specification is set based on the residual voltage amplitude after the line voltage of the three-phase short circuit, two-phase ground short circuit, and two-phase phase-to-phase short circuit faults and the phase voltage of the single-phase ground short circuit fault.

[0042] Preferably, based on the fault response characteristic data of each of the aforementioned units, clustering is performed on each of the equivalent photovoltaic power generation units to obtain multiple clusters, including: Based on the similarity between the fault response curves of each equivalent photovoltaic power generation unit, the equivalent photovoltaic power generation units are clustered to obtain multiple clusters; wherein, the similarity is determined according to the shape of the fault response curve, voltage drop depth, power peak, steady-state value and recovery time.

[0043] In one embodiment, the similarity of fault response curves of each equivalent photovoltaic (PV) power generation unit is compared: equivalent PV power generation units with highly similar response curve shapes, voltage drop depths, peak power, steady-state values, and recovery times are grouped into the same final cluster; equivalent PV power generation units with significantly different response characteristics and incoordination are grouped into different final clusters. Specifically, after clustering the PV power plant, it is also necessary to determine the coherence between equivalent PV power generation units within the same cluster. If the coherence is good, the active and reactive power flowing through the transmission lines between the PV power plant and the external power grid, as well as the voltage of the high-voltage side bus of the PV power plant's main transformer (i.e., the voltage at the grid connection point) and the current injected into the external power grid are further compared to verify the rationality of the clustering, ensuring that each cluster accurately reflects the fault response characteristics of different PV power generation units within the PV power plant. If the coherence or rationality does not meet the requirements, the clustering rules are adjusted and clustering is performed again until the fault response characteristics of equivalent PV power generation units within each cluster tend to be consistent.

[0044] Step S103: Calculate the equivalent parameters of the target photovoltaic power station, and based on each cluster and each equivalent parameter, convert the topology model into a second equivalent model; wherein, the equivalent parameters include equivalent photovoltaic power generation unit parameters, equivalent transformer parameters, and equivalent collection line parameters.

[0045] It should be noted that calculating the equivalent parameters of the target photovoltaic power station and converting the topology model into a second equivalent model based on each cluster and each equivalent parameter means: calculating the equivalent photovoltaic power generation unit parameters, equivalent transformer parameters, and equivalent collector line parameters for each cluster obtained by secondary clustering. After obtaining the various equivalent parameters, the original photovoltaic power generation units, transformers, and collector lines that need to be replaced in the topology model are determined according to the division results of each cluster. These are then replaced with the corresponding equivalent photovoltaic power generation units, equivalent transformers, and equivalent collector lines, while retaining the main transformer, reactive power compensation equipment, and their connection relationships in the topology model. The replaced equivalent components are connected to the retained equipment according to the original electrical wiring relationships, thus converting the topology model into a second equivalent model.

[0046] Preferably, the calculation of the equivalent parameters of the target photovoltaic power station includes: For any cluster, the active power, reactive power and apparent power of all photovoltaic power generation units in the cluster are superimposed to obtain the equivalent active power, equivalent reactive power and the first equivalent apparent power. The equivalent active power, the equivalent reactive power and the first equivalent apparent power are used as the equivalent photovoltaic power generation unit parameters corresponding to the cluster. The apparent power of the box transformers corresponding to each photovoltaic power generation unit in the cluster is superimposed to obtain the second equivalent apparent power, and the impedance of each box transformer is equalized to obtain the first equivalent impedance. The second equivalent apparent power and the first equivalent impedance are used as the equivalent box transformer parameters corresponding to the cluster. For any collector line, based on the impedance and current of each segment of the collector line, each segment is made into a second equivalent impedance of the collector line. Based on the second equivalent impedance and current of each collector line, the collector lines are combined in parallel to obtain a third equivalent impedance. The third equivalent impedance is used as the parameter of the equivalent collector line.

[0047] In one embodiment, the equivalent model of the photovoltaic power generation unit is as follows: Figure 4 As shown, within the same cluster By merging several photovoltaic power generation units, an equivalent photovoltaic power generation unit can be obtained, the structure of which is as follows: Figure 5 As shown. Calculate the active power of the equivalent photovoltaic power generation unit. reactive power and apparent power The equivalent photovoltaic power generation unit parameters are obtained using the following calculation formula: ; in, , The number of photovoltaic power generation units within the same cluster; For the first The active power of each photovoltaic power generation unit; For the first The reactive power of each photovoltaic power generation unit; For the first Apparent power of each photovoltaic power generation unit.

[0048] In one embodiment, the transformer includes a main transformer and a box-type transformer. The main transformer refers to the step-up transformer that connects the photovoltaic power station to the external power grid. It does not require equivalent parameter calculation; the parameters of the main transformer in the topology model are directly used as equivalent parameters to ensure consistency between the equivalent parameters of the main transformer and the actual equipment. The box-type transformer refers to the transformer connected to each photovoltaic power generation unit. Its equivalent parameters include two cases: identical impedance and different impedance. The equivalent impedance of the box-type transformer needs to be calculated separately for both cases. The apparent power of the equivalent box-type transformer... In both cases, the apparent power of a single box-type transformer is superimposed, and the specific calculation formula is as follows: ; in, The number of box-type transformers within the same cluster; For the first Apparent power of a box-type transformer.

[0049] Preferably, the step of equalizing the impedances of each of the box-type transformers to obtain a first equivalent impedance includes: When the impedance of each of the box-type transformers is the same, the first equivalent impedance is obtained by dividing the impedance by the number of each of the box-type transformers. When the impedances of the various box-type transformers are different, the first equivalent impedance is calculated under the condition that the total power loss of the cluster before and after the equivalent impedance is equal.

[0050] In one embodiment, when all box-type transformers within the same cluster have the same impedance, the impedance of a single box-type transformer is divided by the number of box-type transformers in the cluster to obtain the equivalent impedance of the equivalent box-type transformer. (i.e., the first equivalent impedance), the specific calculation formula is as follows: ; in, The number of box-type transformers within the same cluster; This represents the impedance of a single box-type transformer.

[0051] In one embodiment, when the impedances of all box-type transformers within the same cluster are different, the impedances of each box-type transformer within the cluster are respectively Voltage drop across the impedance for: ; in, For the first The impedance of a box-type transformer; For the flow through the first The current of the box-type transformer; No. Apparent power of a box-type transformer; This refers to the terminal voltage. The power loss of a single box-type transformer. for: ; in, for The conjugate complex number. The power loss of each box-type transformer within the same cluster is calculated and summed to obtain the actual total power loss of the entire cluster. The specific calculation formula is as follows: ; in, This represents the total current flowing through the entire cluster. Let be the equivalent impedance of the equivalent transformer. The cluster is equivalent to a single equivalent transformer, and the power loss of the equivalent transformer is expressed as: ; in, This represents the voltage drop across the equivalent impedance. for The conjugate of complex numbers, This represents the current flowing through the equivalent impedance. The actual total power loss of all box-type transformers within the cluster is equal to the power loss of the equivalent box-type transformer, thus yielding the equivalent impedance of box-type transformer clusters with different impedances. : .

[0052] In one embodiment, a single collector line consists of multiple line segments. The equivalence objective is to treat these multiple segments as a single line, thereby reducing the number of line models in the simulation and ensuring that the dynamic characteristics of the equivalenced line are consistent with the original multiple line segments. The formula for calculating the power loss on the impedance of each segment of the collector line is as follows: ; in, For the first Power loss of a section of the line; For the first Voltage drop at both ends of the line segment; For the flow through the first The current in the section of the line; for The conjugate of complex numbers; For the first The impedance of this section of the line. The total power loss of this collector line. for: ; in, The current flowing through a single line; This represents the number of segments on the collector line. The equivalent impedance of a single collector line is calculated. (That is, the second equivalent impedance) is: ; in, This refers to the current flowing through the collector line.

[0053] In one embodiment, such as Figure 6 As shown, for a grid-connected photovoltaic system with multiple branches of photovoltaic generators connected in parallel, each branch is configured with a separate equivalent line impedance. The total current flowing into all branches... The calculation formula is: ; in, The number of branch roads; For the inflow of the first The current in each branch; For the first The number of photovoltaic generator sets on each branch road; Let represent the current flowing into a single photovoltaic generator. Calculate the power loss of each branch: ; in, For the first Power loss of each branch; For the first Find the equivalent impedance of each branch. Calculate the total power loss of all branches. : ; in, The total equivalent impedance (i.e., the third equivalent impedance) of the equivalent collector lines in a photovoltaic grid-connected system is as follows: .

[0054] Preferably, the step of converting the topology model into a second equivalent model based on each of the clusters and each of the equivalent parameters includes: Based on each cluster, determine the photovoltaic power generation units, box transformers, and collection lines that need to be converted in the topology model; Based on the equivalent parameters, the photovoltaic power generation units, box-type transformers and collector lines that need to be converted are respectively converted into equivalent photovoltaic power generation units, equivalent box-type transformers and equivalent collector lines; Based on the electrical wiring relationships of the topology model, the converted equivalent photovoltaic power generation unit, equivalent transformer and equivalent collector line are connected to the main transformer and reactive power compensation equipment of the topology model to obtain the second equivalent model.

[0055] In one embodiment, in simulation software, based on the topology model, the photovoltaic power generation units, box-type transformers, and collector lines corresponding to each cluster can be replaced with corresponding equivalent components, and the equivalent parameters of each equivalent component can be entered. For example... Figure 7 As shown, each equivalent photovoltaic power generation unit, equivalent transformer, equivalent collector line, main transformer, and reactive power compensation equipment are modeled and connected to obtain the second equivalent model. In particular, the main transformer, reactive power compensation equipment, and supporting step-up transformer directly adopt the component parameters and modeling method in the topology model. The control mode and control target of the reactive power compensation equipment are kept consistent with the topology model, all set to voltage control mode with the control target being the grid connection voltage of the photovoltaic power station.

[0056] Step S104: Compare the output data of the topology model and the second equivalent model under the same simulation conditions. If the comparison result meets the preset conditions, the second equivalent model is used as the equivalent model of the target photovoltaic power station.

[0057] It should be noted that comparing the output data of the topology model and the second equivalent model under the same simulation conditions, and if the comparison result meets the preset conditions, then using the second equivalent model as the equivalent model of the target photovoltaic power station means that after the construction of the second equivalent model is completed, using the topology model as a reference and the second equivalent model as the model to be verified, electromagnetic transient simulation calculations are performed under the completely identical initial simulation conditions and fault conditions. Output electrical quantity data such as voltage, current, active power, and reactive power of the two models are obtained in multiple preset time periods. The deviation values ​​of the second equivalent model relative to the topology model in each output electrical quantity are calculated item by item. If the maximum deviation value of all output electrical quantities in all preset time periods is within the preset error range, then the simulation accuracy of the second equivalent model is determined to meet the requirements, and it is used as the final equivalent model of the target photovoltaic power station that can be put into engineering use.

[0058] Preferably, after comparing the output data of the topology model and the second equivalent model under the same simulation conditions, the method further includes: If the comparison result does not meet the preset conditions, the source of the deviation is determined based on the deviation characteristics of the output data. When the judgment bias originates from clustering, clustering is re-executed; when the judgment error originates from the calculation of equivalent parameters, the equivalent parameters are recalculated until the adjusted comparison results meet the preset conditions.

[0059] In one embodiment, the photovoltaic power generation units in both the topology model and the second equivalent model are set to rated output state. A three-phase short-circuit ground fault is set at the grid connection point of the photovoltaic power station, and the voltage drop is set to [value missing]. , , Simulated working conditions, The rated voltage at the grid connection point is used. Simulation calculations for various operating conditions are performed in the simulation software, obtaining simulation waveforms and data for voltage, current, active power, and reactive power under each condition for both models. Based on the simulated active and reactive power response characteristics, the data is divided into three time periods: before the disturbance (A period), during the disturbance (B period), and after the disturbance (C period). Based on the simulated active and reactive power response characteristics, time periods B and C are further divided into transient and steady-state intervals. Time period B is further divided into transient interval B1 and steady-state interval B2, and time period C is divided into transient interval C1 and steady-state interval C2. The calculations are performed on the topology model and the second equivalent model under rated power conditions when a three-phase ground fault occurs at the grid connection point and the voltage drops to [value missing]. , , The simulation data deviation is used to evaluate the accuracy of the second equivalent model. The electrical quantities included in the simulation deviation calculation are: voltage, current, active power, and reactive power.

[0060] Furthermore, if the maximum deviation of all electrical quantities within all voltage dip specifications and all intervals is within the preset error range, then the simulation accuracy of the second equivalent model is deemed to meet the requirements, and the model validity verification is completed. If the simulation of the second equivalent model shows deviations, poor waveform consistency, and is manifested as large dispersion of fault responses of photovoltaic power generation units within the same cluster, obvious bifurcation of transient process waveforms, and overall mismatch of dynamic response trends under multiple voltage dip conditions, then it indicates that the selection of fault response similarity indicators during clustering is unreasonable and the cluster coherence does not meet the requirements. This type of deviation is caused by unreasonable secondary clustering rules and clustering indicators, and it is necessary to return to readjust the clustering indicators and re-cluster for verification. If the simulation only shows that the transient waveform changes in a consistent trend, that only the steady-state amplitude has a fixed offset, or that only a single electrical quantity or a single voltage drop condition has an excessive deviation, and that the fault response within the cluster is well-coordinated, then it indicates that the clustering is reasonable and the error is caused by the calculation method of the equivalent parameters of the photovoltaic power generation unit, the box transformer, or the collector line, the equivalent merging strategy, or the parameter value deviation. There is no need to adjust the clustering; it is only necessary to return the optimized equivalent parameter calculation method and parameter values.

[0061] This invention, through obtaining a topology model and clustering photovoltaic power generation units based on photovoltaic inverter models, can initially compress the model size according to the inherent attributes of the equipment, obtaining a first equivalent model for subsequent simulation. By setting fault conditions at the grid connection point of the first equivalent model and obtaining fault response characteristic data of each equivalent photovoltaic power generation unit, and then performing secondary clustering on each equivalent photovoltaic power generation unit accordingly, the clustering results can reflect the dynamic behavior differences of each photovoltaic power generation unit during the fault transient process, ensuring that photovoltaic power generation units within the same cluster respond consistently under grid disturbances. By calculating equivalent parameters including equivalent photovoltaic power generation unit parameters, equivalent transformer parameters, and equivalent collector line parameters, and converting the topology model into a second equivalent model accordingly, the electrical structure of the equivalent model can be made equivalent to the topology model while reducing the number of simulation units. By comparing and verifying the output data of the topology model and the second equivalent model under the same operating conditions, the deviation of the equivalent model can be quantitatively assessed, ensuring that the final output equivalent model has reliable simulation accuracy. Compared to existing technologies that fail to adequately consider the differences in fault response characteristics, resulting in insufficient accuracy of transient simulation, this application can perform equivalent modeling based on the dynamic behavior of photovoltaic power plants during fault ride-through, thereby improving the electromagnetic transient simulation accuracy of the equivalent model.

[0062] Optionally, in this embodiment of the invention, obtaining the topology model of the target photovoltaic power station includes: The constituent components of the target photovoltaic power station are determined; wherein, the constituent components include photovoltaic power generation units, box-type transformers, collector lines, main transformers and reactive power compensation equipment, the photovoltaic power generation units include photovoltaic inverters, photovoltaic arrays and filters, the collector lines connect the photovoltaic power generation units and the box-type transformers, and one photovoltaic power generation unit corresponds to one box-type transformer; Based on the electrical wiring relationship of the target photovoltaic power station, the constituent components are connected to obtain a topology model.

[0063] The embodiments of the present invention determine the components of a photovoltaic power station and the electrical wiring relationships between the components, and construct a topology model accordingly, which can provide a modeling benchmark for subsequent clustering and equivalent parameter calculation.

[0064] Optionally, in this embodiment of the invention, the step of clustering the photovoltaic power generation units under each collector line in the topology model based on the photovoltaic inverter model to obtain a first equivalent model includes: Photovoltaic power generation units with the same photovoltaic inverter model under the same collector line within the topology model are grouped together to obtain multiple first clusters; Each photovoltaic power generation unit in each of the first clusters is equivalent to an equivalent photovoltaic power generation unit, and the topology model is converted into a first equivalent model based on each of the equivalent photovoltaic power generation units.

[0065] This invention, by grouping photovoltaic power generation units with the same model of photovoltaic inverter under the same collector line into a group and equating each group with an equivalent photovoltaic power generation unit, can initially compress the detailed topology model into a controllable alternative equivalent model, thereby reducing the number of calculation objects in subsequent fault simulation.

[0066] Optionally, in this embodiment of the invention, the step of setting up fault conditions at the grid connection point of the first equivalent model and performing simulation analysis to obtain fault response characteristic data of each equivalent photovoltaic power generation unit within the first equivalent model includes: The equivalent photovoltaic power generation units in the first equivalent model are set to operate at rated power. Multiple fault types are set at the grid connection point of the first equivalent model, and electromagnetic transient simulation calculations are performed under each fault type according to the preset voltage drop specifications to obtain the fault response curves of each equivalent photovoltaic power generation unit under each fault type. The aforementioned fault response curves are used as fault response characteristic data.

[0067] The embodiments of the present invention can obtain the response curves of each equivalent photovoltaic power generation unit under various fault types by setting the rated power state, setting multiple fault types at the grid connection point, and performing electromagnetic transient simulation according to the preset voltage drop specifications, thereby providing data support for subsequent secondary clustering based on fault response characteristics.

[0068] Optionally, in this embodiment of the invention, the step of clustering each equivalent photovoltaic power generation unit based on each of the fault response characteristic data to obtain multiple clusters includes: Based on the similarity between the fault response curves of each equivalent photovoltaic power generation unit, the equivalent photovoltaic power generation units are clustered to obtain multiple clusters; wherein, the similarity is determined according to the shape of the fault response curve, voltage drop depth, power peak, steady-state value and recovery time.

[0069] This invention, through clustering based on the similarity of the fault response curves of each equivalent photovoltaic power generation unit, can group equivalent photovoltaic power generation units with similar dynamic behaviors into the same cluster, enabling the equivalent model to accurately reproduce the dynamic response of the photovoltaic power station during fault ride-through.

[0070] Optionally, in this embodiment of the invention, calculating the equivalent parameters of the target photovoltaic power station includes: For any cluster, the active power, reactive power and apparent power of all photovoltaic power generation units in the cluster are superimposed to obtain the equivalent active power, equivalent reactive power and the first equivalent apparent power. The equivalent active power, the equivalent reactive power and the first equivalent apparent power are used as the equivalent photovoltaic power generation unit parameters corresponding to the cluster. The apparent power of the box transformers corresponding to each photovoltaic power generation unit in the cluster is superimposed to obtain the second equivalent apparent power, and the impedance of each box transformer is equalized to obtain the first equivalent impedance. The second equivalent apparent power and the first equivalent impedance are used as the equivalent box transformer parameters corresponding to the cluster. For any collector line, based on the impedance and current of each segment of the collector line, each segment is made into a second equivalent impedance of the collector line. Based on the second equivalent impedance and current of each collector line, the collector lines are combined in parallel to obtain a third equivalent impedance. The third equivalent impedance is used as the parameter of the equivalent collector line.

[0071] By calculating the equivalent power generation unit parameters, equivalent transformer parameters, and equivalent collector line parameters, this invention can ensure that the total power transmission capacity and impedance characteristics of each component are matched before and after equivalence, making the equivalent model and the topology model equivalent in electrical performance.

[0072] Optionally, in this embodiment of the invention, the step of equalizing the impedance of each of the box-type transformers to obtain a first equivalent impedance includes: When the impedance of each of the box-type transformers is the same, the first equivalent impedance is obtained by dividing the impedance by the number of each of the box-type transformers. When the impedances of the various box-type transformers are different, the first equivalent impedance is calculated under the condition that the total power loss of the cluster before and after the equivalent impedance is equal.

[0073] By distinguishing between cases where the transformer substation impedance is the same and cases where it is different, and calculating the equivalent impedance separately, the impedance parameters of the equivalent transformer substation can accurately match the actual loss characteristics of the original cluster under different engineering configurations, thus avoiding parameter deviations caused by using a single calculation method.

[0074] Optionally, in this embodiment of the invention, converting the topology model into a second equivalent model based on each of the clusters and each of the equivalent parameters includes: Based on each cluster, determine the photovoltaic power generation units, box transformers, and collection lines that need to be converted in the topology model; Based on the equivalent parameters, the photovoltaic power generation units, box-type transformers and collector lines that need to be converted are respectively converted into equivalent photovoltaic power generation units, equivalent box-type transformers and equivalent collector lines; Based on the electrical wiring relationships of the topology model, the converted equivalent photovoltaic power generation unit, equivalent transformer and equivalent collector line are connected to the main transformer and reactive power compensation equipment of the topology model to obtain the second equivalent model.

[0075] This invention determines the components to be converted based on cluster division, converts them into corresponding equivalent components according to equivalent parameters, and then connects the equivalent components to the retained main transformer and reactive power compensation equipment according to the electrical wiring relationship of the original topology. This simplifies the model scale while fully preserving the interface characteristics between the photovoltaic power station and the external power grid, as well as the control response capabilities of key equipment within the station.

[0076] Optionally, in this embodiment of the invention, after comparing the output data of the topology model and the second equivalent model under the same simulation conditions, the method further includes: If the comparison result does not meet the preset conditions, the source of the deviation is determined based on the deviation characteristics of the output data. When the judgment bias originates from clustering, clustering is re-executed; when the judgment error originates from the calculation of equivalent parameters, the equivalent parameters are recalculated until the adjusted comparison results meet the preset conditions.

[0077] This invention, through determining the source of deviations that do not meet preset conditions, and accordingly selecting to re-cluster or recalculate equivalent parameters until the requirements are met, can pinpoint the root cause of errors in the equivalent model, thereby avoiding blind adjustments and achieving model accuracy optimization with the fewest iterations.

[0078] like Figure 8 As shown, based on the above method embodiments, corresponding apparatus embodiments are provided; One embodiment of the present invention provides an equivalent modeling device for photovoltaic power plants for electromagnetic transient simulation, comprising: a first clustering module 801, a second clustering module 802, an equivalent parameter calculation module 803, and a simulation verification module 804; The first clustering module 801 is used to obtain the topology model of the target photovoltaic power station, and based on the photovoltaic inverter model, to cluster the photovoltaic power generation units under each collector line in the topology model to obtain the first equivalent model. The second clustering module 802 is used to set up fault conditions at the grid connection point of the first equivalent model and perform simulation analysis to obtain fault response characteristic data of each equivalent photovoltaic power generation unit in the first equivalent model, and to cluster each equivalent photovoltaic power generation unit based on the fault response characteristic data to obtain multiple clusters. The equivalent parameter calculation module 803 is used to calculate the equivalent parameters of the target photovoltaic power station, and convert the topology model into a second equivalent model based on each cluster and each equivalent parameter; wherein, the equivalent parameters include equivalent photovoltaic power generation unit parameters, equivalent transformer parameters, and equivalent collection line parameters; The simulation verification module 804 is used to compare the output data of the topology model and the second equivalent model under the same simulation conditions. If the comparison result meets the preset conditions, the second equivalent model is used as the equivalent model of the target photovoltaic power station.

[0079] Optionally, in this embodiment of the invention, the first clustering module 801 includes: a component acquisition submodule and a component connection submodule; The component acquisition submodule is used to determine the constituent components of the target photovoltaic power station; wherein, the constituent components include photovoltaic power generation units, box-type transformers, collector lines, main transformers and reactive power compensation equipment, the photovoltaic power generation units include photovoltaic inverters, photovoltaic arrays and filters, the collector lines connect the photovoltaic power generation units and the box-type transformers, and one photovoltaic power generation unit corresponds to one box-type transformer; The component connection submodule is used to connect each of the constituent components according to the electrical wiring relationship of the target photovoltaic power station to obtain a topology model.

[0080] The embodiments of the present invention determine the components of a photovoltaic power station and the electrical wiring relationships between the components, and construct a topology model accordingly, which can provide a modeling benchmark for subsequent clustering and equivalent parameter calculation.

[0081] Optionally, in this embodiment of the invention, the first clustering module 801 further includes: a first clustering submodule and a first model conversion submodule; The first clustering submodule is used to group photovoltaic power generation units with the same photovoltaic inverter model under the same power collection line within the topology model into a group, thereby obtaining multiple first clusters; The first model conversion submodule is used to convert all photovoltaic power generation units in each of the first clusters into an equivalent photovoltaic power generation unit, and convert the topology model into a first equivalent model based on each of the equivalent photovoltaic power generation units.

[0082] This invention, by grouping photovoltaic power generation units with the same model of photovoltaic inverter under the same collector line into a group and equating each group with an equivalent photovoltaic power generation unit, can initially compress the detailed topology model into a controllable alternative equivalent model, thereby reducing the number of calculation objects in subsequent fault simulation.

[0083] Optionally, in this embodiment of the invention, the second clustering module 802 includes: a power setting submodule, a fault simulation submodule, and a data confirmation submodule; The power setting submodule is used to set each equivalent photovoltaic power generation unit in the first equivalent model to operate at the rated power state. The fault simulation submodule is used to set multiple fault types at the grid connection point of the first equivalent model, and perform electromagnetic transient simulation calculations under each fault type according to the preset voltage drop specifications, so as to obtain the fault response curves of each equivalent photovoltaic power generation unit under each fault type. The data confirmation submodule is used to take each of the fault response curves as fault response characteristic data.

[0084] The embodiments of the present invention can obtain the response curves of each equivalent photovoltaic power generation unit under various fault types by setting the rated power state, setting multiple fault types at the grid connection point, and performing electromagnetic transient simulation according to the preset voltage drop specifications, thereby providing data support for subsequent secondary clustering based on fault response characteristics.

[0085] Optionally, in this embodiment of the invention, the second clustering module 802 further includes: a second clustering submodule; The second clustering submodule is used to cluster each equivalent photovoltaic power generation unit according to the similarity between the fault response curves of each equivalent photovoltaic power generation unit to obtain multiple clusters; wherein, the similarity is determined according to the shape of the fault response curve, voltage drop depth, power peak, steady state value and recovery time.

[0086] This invention, through clustering based on the similarity of the fault response curves of each equivalent photovoltaic power generation unit, can group equivalent photovoltaic power generation units with similar dynamic behaviors into the same cluster, enabling the equivalent model to accurately reproduce the dynamic response of the photovoltaic power station during fault ride-through.

[0087] Optionally, in this embodiment of the invention, the equivalent parameter calculation module 803 includes: an equivalent photovoltaic power generation unit parameter calculation submodule, an equivalent box-type transformer parameter calculation submodule, and an equivalent collector line parameter calculation submodule; The equivalent photovoltaic power generation unit parameter calculation submodule is used to superimpose the active power, reactive power and apparent power of all photovoltaic power generation units in any cluster for any cluster, respectively, to obtain equivalent active power, equivalent reactive power and first equivalent apparent power, and use the equivalent active power, the equivalent reactive power and the first equivalent apparent power as the equivalent photovoltaic power generation unit parameters corresponding to the cluster; The equivalent transformer parameter calculation submodule is used to superimpose the apparent power of the box transformers corresponding to each photovoltaic power generation unit in the cluster to obtain the second equivalent apparent power, and to equalize the impedance of each box transformer to obtain the first equivalent impedance. The second equivalent apparent power and the first equivalent impedance are used as the equivalent transformer parameters corresponding to the cluster. The equivalent collector line parameter calculation submodule is used to, for any collector line, determine the second equivalent impedance of each line based on the impedance and current of each segment of the collector line, and then combine the collector lines in parallel based on the second equivalent impedance and current of each collector line to obtain a third equivalent impedance, and use the third equivalent impedance as the equivalent collector line parameter.

[0088] By calculating the equivalent power generation unit parameters, equivalent transformer parameters, and equivalent collector line parameters, this invention can ensure that the total power transmission capacity and impedance characteristics of each component are matched before and after equivalence, making the equivalent model and the topology model equivalent in electrical performance.

[0089] Optionally, in this embodiment of the invention, the equivalent box transformer parameter calculation submodule includes: a first equivalent box transformer impedance calculation unit and a second equivalent box transformer impedance calculation unit; The first equivalent box transformer impedance calculation unit is used to divide the impedance by the number of box transformers to obtain the first equivalent impedance when the impedances of each box transformer are the same. The second equivalent box transformer impedance calculation unit is used to calculate the first equivalent impedance when the impedances of each of the box transformers are different, based on the condition that the total power loss of the cluster before and after equivalence is equal.

[0090] By distinguishing between cases where the transformer substation impedance is the same and cases where it is different, and calculating the equivalent impedance separately, the impedance parameters of the equivalent transformer substation can accurately match the actual loss characteristics of the original cluster under different engineering configurations, thus avoiding parameter deviations caused by using a single calculation method.

[0091] Optionally, in this embodiment of the invention, the equivalent parameter calculation module 803 further includes: a component confirmation submodule, a component conversion submodule, and a second model conversion submodule; The component confirmation submodule is used to determine, based on each cluster, the photovoltaic power generation unit, box transformer, and collector line that need to be converted in the topology model; The component conversion submodule is used to convert the photovoltaic power generation unit, box-type transformer and collector line to be converted into equivalent photovoltaic power generation unit, equivalent box-type transformer and equivalent collector line respectively according to the equivalent parameters. The second model conversion submodule is used to connect the converted equivalent photovoltaic power generation unit, equivalent transformer and equivalent collection line to the main transformer and reactive power compensation equipment of the topology model according to the electrical wiring relationship of the topology model, so as to obtain the second equivalent model.

[0092] This invention determines the components to be converted based on cluster division, converts them into corresponding equivalent components according to equivalent parameters, and then connects the equivalent components to the retained main transformer and reactive power compensation equipment according to the electrical wiring relationship of the original topology. This simplifies the model scale while fully preserving the interface characteristics between the photovoltaic power station and the external power grid, as well as the control response capabilities of key equipment within the station.

[0093] Optionally, in this embodiment of the invention, after the simulation verification module 804, the system further includes: a deviation source determination submodule and a remodeling submodule; The deviation source determination submodule is used to determine the deviation source based on the deviation characteristics of the output data if the comparison result does not meet the preset conditions. The remodeling submodule is used to re-execute clustering when the judgment deviation originates from clustering, and to recalculate the equivalent parameters when the judgment error originates from the calculation of equivalent parameters, until the adjusted comparison result meets the preset conditions.

[0094] This invention, through determining the source of deviations that do not meet preset conditions, and accordingly selecting to re-cluster or recalculate equivalent parameters until the requirements are met, can pinpoint the root cause of errors in the equivalent model, thereby avoiding blind adjustments and achieving model accuracy optimization with the fewest iterations.

[0095] It is understood that the above-described device embodiments correspond to the method embodiments of the present invention, and can implement the photovoltaic power plant equivalent modeling method for electromagnetic transient simulation provided by any of the above-described method embodiments of the present invention.

[0096] This invention employs a first clustering module 801 to acquire a topology model and cluster photovoltaic power generation units based on the photovoltaic inverter model. This allows for the initial compression of the model size based on the inherent attributes of the equipment, resulting in a first equivalent model for subsequent simulations. A second clustering module 802 sets up fault conditions at the grid connection point of the first equivalent model and acquires fault response characteristic data for each equivalent photovoltaic power generation unit. Based on this, a second clustering is performed on each equivalent photovoltaic power generation unit, enabling the clustering results to reflect the dynamic behavioral differences of each photovoltaic power generation unit during fault transients, ensuring the stability of the photovoltaic power generation units within the same cluster. The photovoltaic power generation units respond consistently under grid disturbances. The equivalent parameter calculation module 803 calculates equivalent parameters, including those of the equivalent photovoltaic power generation units, equivalent transformer substations, and equivalent collector lines, and converts the topology model into a second equivalent model. This reduces the number of simulation units while ensuring the electrical structure of the equivalent model is equivalent to the topology model. The simulation verification module 804 compares and verifies the output data of the topology model and the second equivalent model under the same operating conditions, quantifying the deviation of the equivalent model and ensuring reliable simulation accuracy of the final output equivalent model. Compared to existing technologies that fail to adequately consider the differences in fault response characteristics, leading to insufficient transient simulation accuracy, this application can perform equivalent modeling based on the dynamic behavior of the photovoltaic power station during fault ride-through, thereby improving the electromagnetic transient simulation accuracy of the equivalent model.

[0097] It should be noted that the device embodiments described above are merely illustrative, and some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can specifically be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0098] Based on the above embodiment of a photovoltaic power plant equivalent modeling method for electromagnetic transient simulation, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements a photovoltaic power plant equivalent modeling method for electromagnetic transient simulation according to any embodiment of the present invention.

[0099] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the terminal device.

[0100] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0101] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0102] Based on the above-described method embodiments, another embodiment of the present invention provides a computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to execute the equivalent modeling method for photovoltaic power plants oriented towards electromagnetic transient simulation described in any of the above-described method embodiments of the present invention.

[0103] The modules / units integrated in the device / terminal equipment, if implemented as software functional units and sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0104] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A photovoltaic power plant equivalent modeling method for electromagnetic transient simulation, characterized in that, include: Obtain the topology model of the target photovoltaic power station, and based on the photovoltaic inverter model, cluster the photovoltaic power generation units under each collector line in the topology model to obtain the first equivalent model; A fault condition is set at the grid connection point of the first equivalent model and simulation analysis is performed to obtain fault response characteristic data of each equivalent photovoltaic power generation unit in the first equivalent model. Based on the fault response characteristic data, each equivalent photovoltaic power generation unit is clustered to obtain multiple clusters. The equivalent parameters of the target photovoltaic power station are calculated, and based on each cluster and each equivalent parameter, the topology model is converted into a second equivalent model; wherein, the equivalent parameters include equivalent photovoltaic power generation unit parameters, equivalent transformer parameters, and equivalent collection line parameters; The output data of the topology model and the second equivalent model under the same simulation conditions are compared. If the comparison result meets the preset conditions, the second equivalent model is used as the equivalent model of the target photovoltaic power station.

2. The photovoltaic power plant equivalent modeling method for electromagnetic transient simulation as described in claim 1, characterized in that, The process of obtaining the topology model of the target photovoltaic power station includes: The constituent components of the target photovoltaic power station are determined; wherein, the constituent components include photovoltaic power generation units, box-type transformers, collector lines, main transformers and reactive power compensation equipment, the photovoltaic power generation units include photovoltaic inverters, photovoltaic arrays and filters, the collector lines connect the photovoltaic power generation units and the box-type transformers, and one photovoltaic power generation unit corresponds to one box-type transformer; Based on the electrical wiring relationship of the target photovoltaic power station, the constituent components are connected to obtain a topology model.

3. The photovoltaic power plant equivalent modeling method for electromagnetic transient simulation as described in claim 1, characterized in that, The first equivalent model is obtained by clustering the photovoltaic power generation units under each collector line in the topology model based on the photovoltaic inverter model, including: Photovoltaic power generation units with the same photovoltaic inverter model under the same collector line within the topology model are grouped together to obtain multiple first clusters; Each photovoltaic power generation unit in each of the first clusters is equivalent to an equivalent photovoltaic power generation unit, and the topology model is converted into a first equivalent model based on each of the equivalent photovoltaic power generation units.

4. The photovoltaic power plant equivalent modeling method for electromagnetic transient simulation as described in claim 1, characterized in that, The step of setting up fault conditions at the grid connection point of the first equivalent model and performing simulation analysis to obtain fault response characteristic data of each equivalent photovoltaic power generation unit within the first equivalent model includes: The equivalent photovoltaic power generation units in the first equivalent model are set to operate at rated power. Multiple fault types are set at the grid connection point of the first equivalent model, and electromagnetic transient simulation calculations are performed under each fault type according to the preset voltage drop specifications to obtain the fault response curves of each equivalent photovoltaic power generation unit under each fault type. The aforementioned fault response curves are used as fault response characteristic data.

5. The photovoltaic power plant equivalent modeling method for electromagnetic transient simulation as described in claim 4, characterized in that, Based on the fault response characteristic data of each of the aforementioned units, clustering is performed on each of the equivalent photovoltaic power generation units to obtain multiple clusters, including: Based on the similarity between the fault response curves of each equivalent photovoltaic power generation unit, the equivalent photovoltaic power generation units are clustered to obtain multiple clusters; wherein, the similarity is determined according to the shape of the fault response curve, voltage drop depth, power peak, steady-state value and recovery time.

6. The photovoltaic power plant equivalent modeling method for electromagnetic transient simulation as described in claim 1, characterized in that, The calculation of the equivalent parameters of the target photovoltaic power station includes: For any cluster, the active power, reactive power and apparent power of all photovoltaic power generation units in the cluster are superimposed to obtain the equivalent active power, equivalent reactive power and the first equivalent apparent power. The equivalent active power, the equivalent reactive power and the first equivalent apparent power are used as the equivalent photovoltaic power generation unit parameters corresponding to the cluster. The apparent power of the box transformers corresponding to each photovoltaic power generation unit in the cluster is superimposed to obtain the second equivalent apparent power, and the impedance of each box transformer is equalized to obtain the first equivalent impedance. The second equivalent apparent power and the first equivalent impedance are used as the equivalent box transformer parameters corresponding to the cluster. For any collector line, based on the impedance and current of each segment of the collector line, each segment is made into a second equivalent impedance of the collector line. Based on the second equivalent impedance and current of each collector line, the collector lines are combined in parallel to obtain a third equivalent impedance. The third equivalent impedance is used as the parameter of the equivalent collector line.

7. The photovoltaic power plant equivalent modeling method for electromagnetic transient simulation as described in claim 6, characterized in that, The step of equalizing the impedances of each of the box-type transformers to obtain the first equivalent impedance includes: When the impedance of each of the box-type transformers is the same, the first equivalent impedance is obtained by dividing the impedance by the number of each of the box-type transformers. When the impedances of the various box-type transformers are different, the first equivalent impedance is calculated under the condition that the total power loss of the cluster before and after the equivalent impedance is equal.

8. The photovoltaic power plant equivalent modeling method for electromagnetic transient simulation as described in claim 1, characterized in that, The step of converting the topology model into a second equivalent model based on each of the clusters and each of the equivalent parameters includes: Based on each cluster, determine the photovoltaic power generation units, box transformers, and collection lines that need to be converted in the topology model; Based on the equivalent parameters, the photovoltaic power generation units, box-type transformers and collector lines that need to be converted are respectively converted into equivalent photovoltaic power generation units, equivalent box-type transformers and equivalent collector lines; Based on the electrical wiring relationships of the topology model, the converted equivalent photovoltaic power generation unit, equivalent transformer and equivalent collector line are connected to the main transformer and reactive power compensation equipment of the topology model to obtain the second equivalent model.

9. The photovoltaic power plant equivalent modeling method for electromagnetic transient simulation as described in claim 1, characterized in that, After comparing the output data of the topology model and the second equivalent model under the same simulation conditions, the method further includes: If the comparison result does not meet the preset conditions, the source of the deviation is determined based on the deviation characteristics of the output data. When the judgment bias originates from clustering, clustering is re-executed; when the judgment error originates from the calculation of equivalent parameters, the equivalent parameters are recalculated until the adjusted comparison results meet the preset conditions.

10. A photovoltaic power plant equivalent modeling device for electromagnetic transient simulation, characterized in that, include: The system comprises a first clustering module, a second clustering module, an equivalent parameter calculation module, and a simulation verification module. The first clustering module is used to obtain the topology model of the target photovoltaic power station, and based on the photovoltaic inverter model, to cluster the photovoltaic power generation units under each collector line in the topology model to obtain the first equivalent model. The second clustering module is used to set up fault conditions at the grid connection point of the first equivalent model and perform simulation analysis to obtain fault response characteristic data of each equivalent photovoltaic power generation unit in the first equivalent model, and to cluster each equivalent photovoltaic power generation unit based on the fault response characteristic data to obtain multiple clusters. The equivalent parameter calculation module is used to calculate the equivalent parameters of the target photovoltaic power station, and based on each cluster and each equivalent parameter, convert the topology model into a second equivalent model; wherein, the equivalent parameters include equivalent photovoltaic power generation unit parameters, equivalent transformer parameters, and equivalent collection line parameters; The simulation verification module is used to compare the output data of the topology model and the second equivalent model under the same simulation conditions. If the comparison result meets the preset conditions, the second equivalent model is used as the equivalent model of the target photovoltaic power station.

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