A new energy station power collection network equivalent modeling method and system

Abstract

This invention discloses an equivalent modeling method and system for power collection networks in new energy power plants. The method includes: acquiring the power plant topology, equipment parameters, and operating data; determining the equivalent impedance of each generator unit to the grid connection point; calculating the amplitude and phase of the generator terminal voltage level by level along the feeder from the grid connection point to obtain the voltage phasor considering the transverse component of the line voltage drop; calculating the effective contribution complex coefficient based on the apparent power and voltage phasor; grouping the generator units based on electrical distance and voltage phase angle; and using the conjugate complex number of the effective contribution complex coefficient to perform weighted correction on the equivalent impedance to obtain the equivalent impedance and equivalent transformer parameters for each group, thus constructing an equivalent model. This invention introduces voltage phase distribution into equivalent modeling, significantly improving the accuracy of the equivalent model, and is suitable for electromechanical or electromagnetic transient simulation of wind farms and photovoltaic power plants.

Description

Technical Field

[0001] This invention belongs to the field of power system simulation and analysis technology, and in particular relates to an equivalent modeling method and system for the power collection network of new energy power plants. Background Technology

[0002] With the continuous growth of installed capacity of new energy sources, the impact of large-scale new energy power plants (such as wind farms and photovoltaic power plants) on the safe and stable operation of the power system is becoming increasingly significant. In power system simulation analysis, detailed modeling of each unit and its connecting lines (including collector lines and box-type transformers) within a new energy power plant would result in a massive simulation model and excessively long computation time, making it difficult to meet actual engineering needs. Therefore, simplifying the internal network of new energy power plants through equivalent modeling is a crucial step in new energy power plant modeling.

[0003] Most existing equivalent methods for power collection networks in renewable energy power plants assume that the voltage phase of each generating unit within the power plant is the same, using only power or electrical distance as the basis for equivalent weighting. For example, the traditional power moment method multiplies the capacity of each unit by its electrical distance to the grid connection point, sums the results, and then divides by the total capacity to obtain the equivalent impedance. However, in actual renewable energy power plants, due to differences in collection line length, transformer phase shift effects, and the influence of line distribution parameters, there is a non-negligible phase difference in the voltage at the generating unit terminals at different locations. Especially under power frequency conditions, the voltage phase difference between the terminal units at the end of long lines and the units at the near end can reach several degrees. Ignoring this phase difference will lead to systematic deviations in the equivalent impedance calculation, thereby affecting the accuracy of the equivalent model's dynamic response during transient processes. Summary of the Invention

[0004] The purpose of this invention is to provide an equivalent modeling method and system for the power collection network of new energy power plants, so as to solve the problem of insufficient equivalent accuracy caused by neglecting the voltage phase difference of the units in the existing equivalent methods.

[0005] In a first aspect, the present invention provides an equivalent modeling method for the power collection network of a new energy power station, comprising: The topology, equipment parameters, and operating data of the target renewable energy power station are obtained. The equipment parameters include the impedance of the collector lines and the parameters of the box-type transformer. The operating data includes the grid connection point voltage and the power at the beginning of each feeder. Based on the aforementioned topology and equipment parameters, determine the equivalent impedance of each unit to the grid connection point; Starting from the grid connection point, the amplitude and phase of the generator terminal voltage of each unit are calculated step by step along each feeder based on the operating data to obtain the voltage phasor that takes into account the transverse component of the line voltage drop. Based on the apparent power of each unit and the voltage phasor, the effective contribution complex coefficient of each unit is calculated, and the phase of the effective contribution complex coefficient is opposite to the phase of the terminal voltage. If a multi-unit equivalent model needs to be constructed, the units are grouped based on the electrical distance and voltage phase angle of each unit; otherwise, all units are grouped into the same group to obtain at least one unit group. For the at least one group of generating units, the equivalent impedance of each generating unit to the grid connection point is weighted and corrected using the conjugate complex number of the effective contribution complex coefficient of each generating unit in the group, and the equivalent impedance of each group of generating units is calculated. The conjugate complex number causes the voltage phase information to participate in the weighting in the form of positive phase. Based on the parameters of the box-type transformer, the equivalent transformer parameters of each unit group are calculated, and based on the equivalent impedance and equivalent transformer parameters of each unit group, an equivalent model of the new energy power station is constructed.

[0006] Secondly, the present invention provides an equivalent modeling system for the power collection network of a new energy power station, comprising: The acquisition module is configured to acquire the topology, equipment parameters and operating data of the target new energy power station. The equipment parameters include the impedance of the collector lines and the parameters of the box-type transformer. The operating data includes the grid connection point voltage and the power at the beginning of each feeder. The module is configured to determine the equivalent impedance of each unit to the grid connection point based on the topology and equipment parameters. The calculation module is configured to take the grid connection point as the starting point and calculate the amplitude and phase of the generator terminal voltage of each unit step by step along each feeder according to the operating data to obtain the voltage phasor that takes into account the transverse component of the line voltage drop. The calculation module is configured to calculate the effective contribution complex coefficient of each unit based on the apparent power of each unit and the voltage phasor, wherein the phase of the effective contribution complex coefficient is opposite to the phase of the terminal voltage. The clustering module is configured to group the units based on the electrical distance and voltage phase angle of each unit if a multi-unit equivalent model needs to be built; otherwise, all units are grouped into the same group to obtain at least one unit group. The correction module is configured to, for the at least one generator group, use the conjugate complex number of the effective contribution complex coefficients of each generator group within the group to perform weighted correction on the equivalent impedance of each generator group to the grid connection point, and calculate the equivalent impedance of each generator group, wherein the conjugate complex number causes the voltage phase information to participate in the weighting in a positive phase form. The module is configured to calculate the equivalent transformer parameters of each unit group based on the parameters of the box-type transformer, and to construct the equivalent model of the new energy power station based on the equivalent impedance and equivalent transformer parameters of each unit group.

[0007] Thirdly, an electronic device is provided, comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the steps of the equivalent modeling method for the power collection network of a new energy power station according to any embodiment of the present invention.

[0008] Fourthly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor performs the steps of the equivalent modeling method for the power collection network of a new energy power station according to any embodiment of the present invention.

[0009] The equivalent modeling method and system for the power collection network of new energy power plants in this application calculates the amplitude and phase of the voltage at the generator terminals of each unit step by step along the feeder, taking into account the transverse component of the voltage drop of the line. For the first time, the voltage phase distribution is introduced into the equivalent modeling of the power collection network of new energy power plants, which overcomes the problem of insufficient equivalent accuracy caused by the traditional method assuming that the voltage phase of each unit is the same. An "effective contribution complex coefficient" was constructed to simultaneously characterize the unit capacity, voltage amplitude, and phase contribution. Its phase is opposite to that of the terminal voltage. Through the conjugate complex number, the phase information participates in the weighted correction of the equivalent impedance in the form of positive phase, thus realizing the accurate quantification of the influence of phase difference on the equivalent impedance. By grouping units by electrical distance and voltage phase angle, units with similar phases and electrical distances are grouped together, further improving the accuracy of the multi-unit equivalent model. Attached Figure Description

[0010] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 A flowchart illustrating an equivalent modeling method for a power collection network at a new energy power plant, provided in an embodiment of the present invention; Figure 2 This is a structural block diagram of an equivalent modeling system for a new energy power station power collection network provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] Please see Figure 1 The diagram shows a flowchart of an equivalent modeling method for a new energy power station collection network according to this application.

[0014] like Figure 1 As shown, the equivalent modeling method for the power collection network of new energy power plants specifically includes the following steps: Step S101: Obtain the topology, equipment parameters, and operating data of the target new energy power station. The equipment parameters include the impedance of the collector lines and the parameters of the box-type transformer. The operating data includes the grid connection point voltage and the power at the beginning of each feeder.

[0015] In this step, the original topology of the target renewable energy power station is obtained. This topology includes the electrical connections of each generator unit (such as photovoltaic inverters or wind turbines), box-type transformers, collector lines, feeders, and main transformer. Topology data can be exported from the power station's design drawings, SCADA system configuration files, or a geographic information system (GIS), and is typically described using a node-branch model, where nodes represent the unit's grid connection point or line junction point, and branches represent collector lines or transformer branches.

[0016] Secondly, obtain the equipment parameters, including the collector line impedance and the box-type transformer parameters. Collector line impedance parameters include resistance per kilometer (Ω / km), reactance (Ω / km), and susceptance (S / km), which can be obtained from the cable or overhead line specification sheet. For example, the resistance per unit length of YJV22-26 / 35-3×95 cable is 0.32Ω / km, and the reactance is 0.12Ω / km. Box-type transformer parameters include rated capacity (MVA), short-circuit impedance percentage (%), turns ratio (high-voltage side / low-voltage side), no-load loss, and load loss. These parameters can be obtained from the equipment's nameplate or test report. For the main transformer, its rated capacity, short-circuit impedance, and turns ratio also need to be obtained. All equipment parameters must be converted to the same voltage reference value (usually the collector line voltage level, such as 35kV) for subsequent impedance calculations.

[0017] Finally, operational data is acquired, including grid connection point voltage and power at each feeder head. Grid connection point voltage data includes voltage amplitude (kV) and phase angle (°), which can be acquired in real-time from the power station's energy management system (EMS) or phasor measurement unit (PMU), or extracted from historical power flow calculations. Feeder head power data includes active power (MW) and reactive power (MVar), typically acquired through smart meters or protection and control devices installed at the feeder head. The sampling frequency can be set to the power frequency period (e.g., one point every 20 milliseconds at 50Hz) as needed for simulation. Operational data should be selected from data under typical steady-state operating conditions of the power station (e.g., during rated power output periods) to ensure the representativeness of the calculated voltage phasors. If used for transient simulation verification, transient waveform data before and after the fault also needs to be acquired.

[0018] After obtaining the above data, it can be stored as a structured data table (such as CSV or Excel format) and imported into simulation software (such as PSASP, PSCAD, or MATLAB) for further processing. The accuracy of data acquisition directly affects the accuracy of isometric modeling; therefore, it is recommended to preprocess the collected data, including removing bad data, smoothing noise, and performing time alignment.

[0019] Step S102: Determine the equivalent impedance of each unit to the grid connection point based on the topology and equipment parameters.

[0020] In this step, after obtaining the topology and equipment parameters, it is necessary to determine the equivalent impedance of each generator set (such as a photovoltaic unit or wind turbine) in the power station to the point of common coupling (PCC). This equivalent impedance includes the sum of the impedances of all electrical components along the path from the generator terminal to the PCC, mainly including the impedance of the box-type transformer, the impedance of the collector line, and the impedance of the main transformer that may be passed through (if the generator set undergoes multi-stage voltage boosting).

[0021] The specific implementation process is as follows: I. Establishing a node-branch topology model The power collection network of the power station is abstracted as an undirected graph, where the nodes include: Unit node (the high-voltage side transformer outlet of each unit); Feeder node (busbar at the beginning of each feeder); Main transformer nodes (low-voltage side and high-voltage side of the main transformer). Grid connection point node (PCC); Branch roads include: Box-type transformer branch: connects the unit node and the feeder node; Collector line branch: connects adjacent unit nodes or feeder nodes and unit nodes on the same feeder line; Main transformer branch: connects the feeder busbar (low voltage side) to the grid connection point (high voltage side); Topological relationships can be stored using an adjacency matrix or a road matrix (i.e., matrix T as described in the specification), where element t ij =1 indicates that node i is directly connected to node j.

[0022] II. Determine the impedance parameters of each branch Impedance of box-type transformer: based on the rated capacity S in the equipment parameters. T (MVA) and short-circuit impedance percentage U k The short-circuit impedance is then reduced to a selected voltage reference value (usually the collector-side voltage level, such as 35kV). The calculation formula is: Z T =(U k % / 100)×( / S T ), Among them, U base Z is the reference voltage (kV). T The actual impedance value (Ω) and transformer resistance R T and reactance X T This can be further separated by load loss and no-load loss. If detailed data is unavailable, X can be approximated. T ≈Z T R T ≈0.1·X T .

[0023] For example, for a 1.5MVA transformer with a short-circuit impedance of 6.5%, and a reference voltage of 35kV, then: Z T =0.065×(35 2 / 1.5)=0.065×816.67 ≈53.08 Ω (referred to the 35kV side).

[0024] In practice, the transformer turns ratio usually needs to be considered, but for simplification, the impedance can be reduced to the same voltage level.

[0025] The impedance of the collector line is calculated based on the line length L (km) and the impedance per unit length z = r + jx (Ω / km), where r is the unit resistance, j is the imaginary part of the complex number, and x is the unit reactance. Z line =L×(r+jx), For example, a 0.5km long YJV22-26 / 35-3×95 cable has a unit resistance of 0.32Ω / km and a unit reactance of 0.12Ω / km. Then: Z line=0.5×(0.32+j0.12)=0.16+j0.06 Ω.

[0026] Main transformer impedance: If the unit needs to be stepped up to a higher voltage level (such as 110kV) via the main transformer, the main transformer impedance must also be calculated to the reference voltage on the collector line side. The calculation method is the same as that for box-type transformers, using the rated capacity and short-circuit impedance percentage of the main transformer.

[0027] III. Determine the path from each generating unit to the grid connection point. Based on the topology, starting from the generator node, search along the branches towards the grid connection point, recording all branches traversed. The path is unique (radial structure) or determined using a shortest path algorithm (for ring networks). The branch order on the path is typically: generator → transformer substation → feeder collector line (potentially multiple segments) → feeder head bus → main transformer (if any) → grid connection point.

[0028] For example, for the third photovoltaic unit on feeder 1, its path is: photovoltaic unit 3 high-voltage side → transformer substation 3 → second collector line (connecting node 2 → node 3) → first collector line (node ​​1 → node 2) → feeder 1 head bus → main transformer low-voltage side → main transformer → grid connection point (110kV side). If the main transformer impedance has been reduced to the 35kV side, then the path includes the transformer substation impedance, the impedances of the two line sections, and the impedance of the main transformer.

[0029] IV. Calculation of Equivalent Impedance Summing the impedances of all branches along the path in series gives the equivalent impedance Z from the unit to the grid connection point. k,eq (Plural form).

[0030] For a single-unit equivalent model, the equivalent impedance of all units and the effective contribution complex coefficients need to be weighted together to obtain the group equivalent impedance. For a multi-unit equivalent model, the equivalent impedance of each unit in the group is calculated separately after grouping, and then used for weighting.

[0031] Step S103: Starting from the grid connection point, calculate the amplitude and phase of the generator terminal voltage of each unit step by step along each feeder according to the operating data, and obtain the voltage phasor that takes into account the transverse component of the line voltage drop.

[0032] In this step, for the line connecting node i and node j, the voltage phasor of node i is known. The line impedance of the lines at nodes i and j The power of the lines flowing through nodes i and j Then the voltage amplitude at node j and phase angle The calculation method is as follows: , , , , In the formula, The longitudinal component of the voltage drop. For the voltage drop transverse component, Let J be the voltage magnitude at node j. Let J be the voltage phase angle at node j. Let be the line resistance of the lines connecting nodes i and j. The line reactance of the lines at nodes i and j. Let be the active power flowing through the lines at nodes i and j. Let be the reactive power of the lines flowing through nodes i and j.

[0033] In one specific embodiment, starting from the grid connection point (PCC), the amplitude and phase of the generator terminal voltage of each unit are calculated step by step along each feeder from the beginning to the end, using the acquired operating data (grid connection point voltage, power at the beginning of each feeder) and the line impedance determined in step S102. Due to the resistance and reactance of the lines, current flowing through the lines will generate a longitudinal component (in the same direction as the voltage) and a transverse component (perpendicular to the voltage), causing a voltage phase shift. Traditional equivalent methods ignore this transverse component and assume that the voltage phase is the same across the entire line. This invention calculates this transverse component step by step to obtain the true voltage phasor of each unit.

[0034] The grid connection point is used as the starting node for the calculation. Let the voltage phasor at the grid connection point be... Among them, amplitude and phase angle The data obtained from the running data in step S101 is typically set to... (As a reference phase). If the substation has a main transformer, the voltage at the grid connection point must first be reduced to the collector line side (e.g., the 35kV side). During the reduction, the actual turns ratio and impedance of the main transformer are considered, and the voltage phasor of the low-voltage side of the main transformer (i.e., the busbar at the beginning of the feeder) is calculated as the common starting point for the calculation of each feeder.

[0035] For a given feeder, the voltage phasor of the feeder's starting node (denoted as node 0) is known. Several generating units are connected to this feeder, and the units are connected in series via collector lines. Starting from the first end, the voltage of the downstream nodes is calculated segment by segment along the power transmission direction (from the first end to the last end).

[0036] Let the voltage phasor of node i be known at present. The line impedance between node i and its downstream adjacent node j is The power flowing through this line is (MVA, where) For merit, (This is for reactive power). The power direction is defined as flowing from node i to node j.

[0037] Then the line current It can be calculated from power and voltage: However, in actual engineering, the voltage drop approximation formula is often used, and there is no need to explicitly calculate the current phase angle.

[0038] Longitudinal component of voltage drop (and (Components in the same direction) and horizontal component (and The vertical component is calculated using the following formula: , , Then the voltage amplitude at node j and phase angle for: , , Note: When When the arctangent value is between -90° and 90°, the voltage drop transverse component in actual power systems is relatively small, so this formula can be used for stable calculation.

[0039] In the step-by-step calculation, the key is to determine the power S flowing through each line. ij For radial feeders, the line power equals the sum of the output power of all units downstream of that node (including units connected to that node, if there are units at the node). Specific method: Starting from the end of the feeder, the power is accumulated in reverse direction towards the beginning. The power of the line connected to the end node j (the last unit) is the output power (apparent power) of that unit itself.

[0040] For intermediate node i, the power of its downstream lines is equal to the power of the unit connected to node i plus the sum of the power of all downstream lines of node i.

[0041] Since the total power at the beginning of each feeder has been obtained in step S101, it can also be calculated recursively from the beginning to the end: given the total power at the beginning, subtract the power of the first generator unit at the beginning to obtain the power of the first section of the line; then subtract the power of the second generator unit to obtain the power of the second section of the line, and so on. The two methods are equivalent. In actual implementation, the power of each line can be pre-calculated by accumulating from the end to the beginning, and then the voltage can be calculated from the beginning to the end.

[0042] Step S104: Calculate the effective contribution complex coefficient of each unit based on the apparent power of each unit and the voltage phasor. The phase of the effective contribution complex coefficient is opposite to the phase of the terminal voltage.

[0043] In this step, the expression for calculating the effective contribution complex coefficient is: , , , , In the formula, The effective contribution complex coefficient of the k-th unit. Let the apparent power modulus of the k-th unit be . Let be the voltage amplitude at the terminals of the k-th generating unit. Let the voltage phase angle of the k-th unit be . For the first Voltage amplitude of the Taiwanese unit The phase rotation factor, The total number of units. Let be the power transmission distribution factor of the k-th unit. Let K be the electrical distance attenuation factor of the k-th unit. The preset attenuation coefficient has a value range of [0.5, 2.0]. Let k be the equivalent electrical distance from the k-th generating unit to the grid connection point. This is the maximum equivalent electrical distance from the generator unit to the grid connection point. , Let be the voltage amplitude normalization factor for the k-th unit. This represents the power change caused by the power increment at the grid connection point. For the power increment of the k-th unit, Let k be the set of lines on the path from the k-th generating unit to the grid connection point. For the first The power of the unit, This refers to the power increase caused at the grid connection point. Let be the power of the k-th unit.

[0044] Step S105: If a multi-unit equivalent model needs to be constructed, the units are grouped based on the electrical distance and voltage phase angle of each unit; otherwise, all units are grouped into the same group to obtain at least one unit group.

[0045] In this step, a feature vector is constructed for each unit, which includes the electrical distance from the unit to the grid connection point and the voltage phase angle of the unit; The feature vectors are normalized. The k-means clustering algorithm is used to cluster the normalized feature vectors into a preset number of categories, resulting in at least one unit group.

[0046] Step S106: For the at least one generator group, the equivalent impedance of each generator group to the grid connection point is weighted and corrected using the conjugate complex number of the effective contribution complex coefficient of each generator group in the group, and the equivalent impedance of each generator group is calculated. The conjugate complex number causes the voltage phase information to participate in the weighting in the form of positive phase.

[0047] In this step, the formula for calculating the equivalent impedance of each unit group is as follows: , In the formula, Let be the equivalent impedance of the g-th unit group. For the g-th unit group, Let be the conjugate complex number of the effective contribution complex coefficients of the k-th generating unit. Let be the equivalent impedance from the k-th generating unit to the grid connection point. Let g be the equivalent voltage amplitude of the g-th group. Let the apparent power modulus of the k-th unit be . Let be the voltage amplitude at the terminal of the kth generator unit.

[0048] Step S107: Calculate the equivalent transformer parameters for each unit group based on the parameters of the box-type transformer, and construct the equivalent model of the new energy power station based on the equivalent impedance and equivalent transformer parameters of each unit group.

[0049] In this step, the equivalent transformer parameters include equivalent capacity, equivalent short-circuit impedance, and equivalent turns ratio, wherein the equivalent turns ratio is taken as the turns ratio of the box-type transformer with the largest equivalent unit capacity. The expression for calculating the equivalent capacity is: , In the formula, For equivalent capacity, Let the transformer capacity of the k-th unit be . This is the g-th unit group; The expression for calculating the equivalent short-circuit impedance is as follows: , In the formula, This is the equivalent short-circuit impedance. Let be the per-unit value of the short-circuit impedance of the k-th unit transformer.

[0050] In one specific embodiment, the construction of the equivalent model requires connecting the equivalent generating unit, equivalent transformer, equivalent collector line impedance, and the original main transformer according to the actual electrical topology. The specific steps are as follows: Determine the model type: Based on the grouping results in step S105, if all units are grouped into the same group, a single-unit equivalent model is constructed; if there are multiple groups, a multi-unit equivalent model is constructed, and the equivalent branches corresponding to each group are connected in parallel to the grid connection point.

[0051] Equivalent unit settings: Capacity: equal to the sum of the rated capacities of all units in the group (e.g., 50MW for a single unit).

[0052] Control parameters: Take the average or typical values ​​of the control parameters of each unit in the group (such as active / reactive control mode, PI parameters, low voltage ride-through characteristics, etc.). For photovoltaic power plants, the output characteristics of the equivalent photovoltaic unit can be set according to the average values ​​of irradiance and temperature of each unit in the group; for wind farms, the power curve of the equivalent wind turbine can be taken as the average curve of the units in the group.

[0053] Equivalent transformer connection: Connect the high-voltage side of the equivalent transformer to one end of the equivalent collector line (impedance), and connect the low-voltage side to the equivalent generator unit.

[0054] The transformer parameters are entered into the simulation model (such as PSASP, PSCAD, MATLAB / Simulink, etc.) according to the above calculation results.

[0055] Equivalent collector impedance: The equivalent impedance calculated in step S106 This impedance serves as the series impedance of the equivalent collector line. Note that this impedance already incorporates the equivalent effects of the transformer substation impedance, the collector line impedance, and the main transformer impedance. Therefore, in actual wiring, this impedance should be placed between the high-voltage side of the equivalent transformer and the grid connection point (or the low-voltage side of the main transformer).

[0056] If the power station has a main transformer (e.g., 35kV / 110kV), the main transformer should be retained separately, modeled using actual parameters, and not equivalent. One end of the equivalent collector line impedance is connected to the low-voltage busbar of the main transformer, and the other end is connected to the high-voltage side of the equivalent transformer.

[0057] Wiring topology: If multiple equivalent units are used, multiple equivalent branches are connected in parallel to the low-voltage side busbar of the main transformer. Each branch includes "equivalent collector line impedance + equivalent transformer + equivalent generator set".

[0058] Model parameter normalization: All impedances should be reduced to the same voltage reference (usually the collector voltage level of 35kV), which can be automatically handled in the simulation software by setting the reference voltage.

[0059] In summary, the method proposed in this application addresses the problem of insufficient equivalence accuracy caused by existing equivalent methods neglecting the voltage phase differences of units at different locations within the power station. The method involves: acquiring the power station topology, equipment parameters, and operating data; determining the equivalent impedance of each unit to the grid connection point; calculating the amplitude and phase of the terminal voltage of each unit stepwise along the feeder from the grid connection point to obtain the voltage phasor considering the transverse component of the line voltage drop; calculating the effective contribution complex coefficient based on the apparent power and voltage phasor; grouping the units based on electrical distance and voltage phase angle; using the conjugate complex number of the effective contribution complex coefficient to perform weighted correction on the equivalent impedance to obtain the equivalent impedance and equivalent transformer parameters for each group, thus constructing an equivalent model; and introducing the voltage phase distribution into the equivalent modeling, significantly improving the equivalence accuracy. This method is suitable for electromechanical or electromagnetic transient simulations of wind farms and photovoltaic power stations.

[0060] Please see Figure 2 The diagram shows a structural block diagram of an equivalent modeling system for a new energy power station collection network according to this application.

[0061] like Figure 2 As shown, the equivalent modeling system 200 for the power collection network of new energy power plants includes an acquisition module 210, a determination module 220, a calculation module 230, a calculation module 240, a clustering module 250, a correction module 260, and a construction module 270.

[0062] The acquisition module 210 is configured to acquire the topology, equipment parameters, and operating data of the target renewable energy power station. The equipment parameters include the collector line impedance and box-type transformer parameters. The operating data includes the grid connection point voltage and the power at the head end of each feeder. The determination module 220 is configured to determine the equivalent impedance of each unit to the grid connection point based on the topology and equipment parameters. The calculation module 230 is configured to calculate the amplitude and phase of the generator terminal voltage of each unit step by step along each feeder, starting from the grid connection point, based on the operating data, to obtain the voltage phasor that takes into account the transverse component of the line voltage drop. The calculation module 240 is configured to calculate the effective contribution complex coefficient of each unit based on the apparent power of each unit and the voltage phasor. The phase of the effective contribution complex coefficient is related to the generator terminal voltage. The voltage phases are opposite; the clustering module 250 is configured to group the units based on the electrical distance and voltage phase angle of each unit if a multi-unit equivalent model needs to be constructed, otherwise all units are grouped into the same group to obtain at least one unit group; the correction module 260 is configured to use the conjugate complex number of the effective contribution complex coefficient of each unit in the group to perform weighted correction on the equivalent impedance of each unit to the grid connection point for the at least one unit group, and calculate the equivalent impedance of each unit group, wherein the conjugate complex number makes the voltage phase information participate in the weighting in the form of positive phase; the construction module 270 is configured to calculate the equivalent transformer parameters of each unit group according to the box transformer parameters, and construct the equivalent model of the new energy power station according to the equivalent impedance and equivalent transformer parameters of each unit group.

[0063] It should be understood that Figure 2 The modules and references described in the document Figure 1 The steps described in the text correspond to those in the method described above. Therefore, the operations, features, and corresponding technical effects described above also apply to the method described in the text. Figure 2 The various modules in the document will not be described in detail here.

[0064] In other embodiments, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor performs the equivalent modeling method for the power collection network of new energy power plants in any of the above method embodiments. In one embodiment, the computer-readable storage medium of the present invention stores computer-executable instructions, which are configured as follows: The topology, equipment parameters, and operating data of the target renewable energy power station are obtained. The equipment parameters include the impedance of the collector lines and the parameters of the box-type transformer. The operating data includes the grid connection point voltage and the power at the beginning of each feeder. Based on the aforementioned topology and equipment parameters, determine the equivalent impedance of each unit to the grid connection point; Starting from the grid connection point, the amplitude and phase of the generator terminal voltage of each unit are calculated step by step along each feeder based on the operating data to obtain the voltage phasor that takes into account the transverse component of the line voltage drop. Based on the apparent power of each unit and the voltage phasor, the effective contribution complex coefficient of each unit is calculated, and the phase of the effective contribution complex coefficient is opposite to the phase of the terminal voltage. If a multi-unit equivalent model needs to be constructed, the units are grouped based on the electrical distance and voltage phase angle of each unit; otherwise, all units are grouped into the same group to obtain at least one unit group. For the at least one group of generating units, the equivalent impedance of each generating unit to the grid connection point is weighted and corrected using the conjugate complex number of the effective contribution complex coefficient of each generating unit in the group, and the equivalent impedance of each group of generating units is calculated. The conjugate complex number causes the voltage phase information to participate in the weighting in the form of positive phase. Based on the parameters of the box-type transformer, the equivalent transformer parameters of each unit group are calculated, and based on the equivalent impedance and equivalent transformer parameters of each unit group, an equivalent model of the new energy power station is constructed.

[0065] Computer-readable storage media may include a stored program area and a stored data area, wherein the stored program area may store an operating system and an application program required for at least one function; the stored data area may store data created based on the use of the equivalent modeling system for the power collection network of new energy power plants. Furthermore, the computer-readable storage medium may include high-speed random access memory, and may also include memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, the computer-readable storage medium may optionally include memory remotely disposed relative to a processor, and these remote memories may be connected to the equivalent modeling system for the power collection network of new energy power plants via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0066] Figure 3 This is a schematic diagram of the structure of the electronic device provided in the embodiment of the present invention, such as... Figure 3 As shown, the device includes a processor 310 and a memory 320. The electronic device may also include an input device 330 and an output device 340. The processor 310, memory 320, input device 330, and output device 340 can be connected via a bus or other means. Figure 3 Taking a bus connection as an example, the memory 320 is the computer-readable storage medium described above. The processor 310 executes various server functions and data processing by running non-volatile software programs, instructions, and modules stored in the memory 320, thereby implementing the equivalent modeling method for the new energy power station power collection network described in the above embodiment. The input device 330 can receive input digital or character information and generate key signal inputs related to user settings and function control of the equivalent modeling system for the new energy power station power collection network. The output device 340 may include a display screen or other display device.

[0067] The aforementioned electronic device can execute the method provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the method provided in the embodiments of the present invention.

[0068] In one implementation, the aforementioned electronic device is applied in an equivalent modeling system for the power collection network of a new energy power station, serving as a client, and includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to: The topology, equipment parameters, and operating data of the target renewable energy power station are obtained. The equipment parameters include the impedance of the collector lines and the parameters of the box-type transformer. The operating data includes the grid connection point voltage and the power at the beginning of each feeder. Based on the aforementioned topology and equipment parameters, determine the equivalent impedance of each unit to the grid connection point; Starting from the grid connection point, the amplitude and phase of the generator terminal voltage of each unit are calculated step by step along each feeder based on the operating data to obtain the voltage phasor that takes into account the transverse component of the line voltage drop. Based on the apparent power of each unit and the voltage phasor, the effective contribution complex coefficient of each unit is calculated, and the phase of the effective contribution complex coefficient is opposite to the phase of the terminal voltage. If a multi-unit equivalent model needs to be constructed, the units are grouped based on the electrical distance and voltage phase angle of each unit; otherwise, all units are grouped into the same group to obtain at least one unit group. For the at least one group of generating units, the equivalent impedance of each generating unit to the grid connection point is weighted and corrected using the conjugate complex number of the effective contribution complex coefficient of each generating unit in the group, and the equivalent impedance of each group of generating units is calculated. The conjugate complex number causes the voltage phase information to participate in the weighting in the form of positive phase. Based on the parameters of the box-type transformer, the equivalent transformer parameters of each unit group are calculated, and based on the equivalent impedance and equivalent transformer parameters of each unit group, an equivalent model of the new energy power station is constructed.

[0069] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of various embodiments or some parts of embodiments.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for equivalent modeling of power collection networks in new energy power plants, characterized in that, include: The topology, equipment parameters, and operating data of the target renewable energy power station are obtained. The equipment parameters include the impedance of the collector lines and the parameters of the box-type transformer. The operating data includes the grid connection point voltage and the power at the beginning of each feeder. Based on the aforementioned topology and equipment parameters, determine the equivalent impedance of each unit to the grid connection point; Starting from the grid connection point, the amplitude and phase of the generator terminal voltage of each unit are calculated step by step along each feeder based on the operating data to obtain the voltage phasor that takes into account the transverse component of the line voltage drop. Based on the apparent power of each unit and the voltage phasor, the effective contribution complex coefficient of each unit is calculated, and the phase of the effective contribution complex coefficient is opposite to the phase of the terminal voltage. If a multi-unit equivalent model needs to be constructed, the units are grouped based on the electrical distance and voltage phase angle of each unit; otherwise, all units are grouped into the same group to obtain at least one unit group. For the at least one group of generating units, the equivalent impedance of each generating unit to the grid connection point is weighted and corrected using the conjugate complex number of the effective contribution complex coefficient of each generating unit in the group, and the equivalent impedance of each group of generating units is calculated. The conjugate complex number causes the voltage phase information to participate in the weighting in the form of positive phase. Based on the parameters of the box-type transformer, the equivalent transformer parameters of each unit group are calculated, and based on the equivalent impedance and equivalent transformer parameters of each unit group, an equivalent model of the new energy power station is constructed.

2. The method for equivalent modeling of a new energy power station collection network according to claim 1, characterized in that, The calculation of the amplitude and phase of the generator terminal voltage of each unit, starting from the grid connection point and based on the operating data, along each feeder, includes: For a line connecting node i and node j, the voltage phasor of node i is known. The line impedance of the lines at nodes i and j The power of the lines flowing through nodes i and j Then the voltage amplitude at node j and phase angle The calculation method is as follows: ， ， ， ， In the formula, The longitudinal component of the voltage drop. For the voltage drop transverse component, Let J be the voltage magnitude at node j. Let J be the voltage phase angle at node j. Let be the line resistance of the lines connecting nodes i and j. The line reactance of the lines at nodes i and j. Let be the active power flowing through the lines at nodes i and j. Let be the reactive power of the lines flowing through nodes i and j.

3. The method for equivalent modeling of a new energy power station collection network according to claim 1, characterized in that, The expression for calculating the effective contribution complex coefficient is as follows: ， ， ， ， In the formula, The effective contribution complex coefficient of the k-th unit. Let the apparent power modulus of the k-th unit be . Let be the voltage amplitude at the terminals of the k-th generating unit. Let be the voltage phase angle of the k-th unit. For the first Voltage amplitude of the Taiwanese unit The phase rotation factor, The total number of units. Let be the power transmission distribution factor of the k-th unit. Let be the electrical distance attenuation factor of the k-th unit. The preset attenuation coefficient has a value range of [0.5, 2.0]. Let k be the equivalent electrical distance from the k-th generating unit to the grid connection point. This is the maximum equivalent electrical distance from the generator unit to the grid connection point. , Let be the voltage amplitude normalization factor for the k-th unit. This represents the power change caused by the power increment at the grid connection point. For the power increment of the k-th unit, Let k be the set of lines on the path from the k-th generating unit to the grid connection point. For the first The power of the unit, This refers to the power increase caused at the grid connection point. Let be the power of the k-th unit.

4. The method for equivalent modeling of a new energy power station collection network according to claim 1, characterized in that, in, The generating units are grouped based on their electrical distance and voltage phase angle, specifically including: Construct a feature vector for each generating unit, the feature vector including the electrical distance from the unit to the grid connection point and the voltage phase angle of the unit; The feature vectors are normalized. The k-means clustering algorithm is used to cluster the normalized feature vectors into a preset number of categories, resulting in at least one unit group.

5. The method for equivalent modeling of a new energy power station collection network according to claim 1, characterized in that, The formula for calculating the equivalent impedance of each unit group is as follows: ， In the formula, Let be the equivalent impedance of the g-th unit group. For the g-th unit group, Let be the conjugate complex number of the effective contribution complex coefficients of the k-th generating unit. Let be the equivalent impedance from the k-th generating unit to the grid connection point. Let g be the equivalent voltage amplitude of the g-th group. Let the apparent power modulus of the k-th unit be . Let be the voltage amplitude at the terminal of the kth generator unit.

6. The method for equivalent modeling of a new energy power station power collection network according to claim 1, characterized in that, The equivalent transformer parameters include equivalent capacity, equivalent short-circuit impedance, and equivalent turns ratio, wherein the equivalent turns ratio is taken as the turns ratio of the box-type transformer with the largest equivalent unit capacity in the equivalent unit group; The expression for calculating the equivalent capacity is: ， In the formula, For equivalent capacity, Let the transformer capacity of the k-th unit be . This is the g-th unit group; The expression for calculating the equivalent short-circuit impedance is as follows: ， In the formula, This is the equivalent short-circuit impedance. Let be the per-unit value of the short-circuit impedance of the k-th unit transformer.

7. A system for equivalent modeling of power collection networks in new energy power plants, characterized in that, include: The acquisition module is configured to acquire the topology, equipment parameters and operating data of the target new energy power station. The equipment parameters include the impedance of the collector lines and the parameters of the box-type transformer. The operating data includes the grid connection point voltage and the power at the beginning of each feeder. The module is configured to determine the equivalent impedance of each unit to the grid connection point based on the topology and equipment parameters. The calculation module is configured to take the grid connection point as the starting point and calculate the amplitude and phase of the generator terminal voltage of each unit step by step along each feeder according to the operating data to obtain the voltage phasor that takes into account the transverse component of the line voltage drop. The calculation module is configured to calculate the effective contribution complex coefficient of each unit based on the apparent power of each unit and the voltage phasor, wherein the phase of the effective contribution complex coefficient is opposite to the phase of the terminal voltage. The clustering module is configured to group the units based on the electrical distance and voltage phase angle of each unit if a multi-unit equivalent model needs to be built; otherwise, all units are grouped into the same group to obtain at least one unit group. The correction module is configured to, for the at least one generator group, use the conjugate complex number of the effective contribution complex coefficients of each generator group within the group to perform weighted correction on the equivalent impedance of each generator group to the grid connection point, and calculate the equivalent impedance of each generator group, wherein the conjugate complex number causes the voltage phase information to participate in the weighting in a positive phase form. The module is configured to calculate the equivalent transformer parameters of each unit group based on the parameters of the box-type transformer, and to construct the equivalent model of the new energy power station based on the equivalent impedance and equivalent transformer parameters of each unit group.

8. An electronic device, characterized in that, include: At least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by a processor, it implements the method described in any one of claims 1 to 6.

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