Wind power plant improved single-machine equivalence method and system oriented to frequency modulation response analysis

Abstract

The invention discloses a frequency modulation response analysis-oriented wind power plant improved single-machine equivalence method and system, and belongs to the technical field of power system new energy station modeling. The method aims at solving the problem that a system frequency response characteristic analysis result is distorted when new energy participates in frequency modulation due to the fact that a traditional wind power plant equivalent modeling method oriented to frequency modulation response analysis in current practical engineering cannot adapt to a frequency modulation response analysis scene. According to the method, wind turbine generators in a wind power plant electromagnetic transient model are divided into two groups according to whether the wind turbine generators participate in frequency modulation or not by taking an active output threshold Tp as a grouping point in a steady state, and the frequency modulation power of an equivalent machine is corrected; calculating an improved virtual inertia coefficient and a droop coefficient of the equivalent machine through the corrected frequency modulation power; in addition, the equivalent machine adopts overspeed load shedding control to realize load shedding operation, and cooperates with virtual inertia control and droop control to participate in system frequency modulation. The method is used for single-machine equivalence of the wind power plant.

Description

Technical Field

[0001] The present invention belongs to the technical field of modeling of new energy stations in power systems, and in particular relates to a method and system for improving the equivalent value of a single machine in a wind farm. Background Art

[0002] With the rapid growth of new energy sources such as wind power and photovoltaic power in my country, the development of the power system presents a "double high" trend (high proportion of new energy access and high power electronics), which puts forward higher requirements for the safe and stable operation of the power system, especially in terms of system inertia. Therefore, from the early planning and construction to the optimization research of the later engineering, the frequency response analysis of the power system is highly dependent on the modeling and simulation of new energy. On the one hand, the high proportion of new energy access introduces a large number of complex power electronic control processes, which leads to the need to reduce the simulation step size to microseconds to ensure the convergence and accuracy of the simulation, which in turn leads to the problem of low simulation calculation efficiency. On the other hand, if the single-machine equivalent or reduced-order method is used to simplify the simulation of the wind farm, it may not be able to fully cover all the operating states of the wind farm, thereby affecting the simulation accuracy of its frequency regulation dynamic response characteristics. When evaluating the frequency regulation capability of the wind farm, simulation errors may lead to unpredictable consequences. Therefore, the existing equivalent model is improved to reduce the demand for simulation resources while maintaining the accuracy of the model, so as to more effectively reflect the operating characteristics of the new energy station.

[0003] Currently, there are many solutions for equivalent modeling of wind farms, such as:

[0004] 1. Zhou Peipeng et al. published "Research on the Structure and Modeling Method of New Energy Station Model for Large-Scale Power System Simulation (III): Electromagnetic Transient Model" Proceedings of the CSEE: 2023, 43(08): 2990-3000. Starting from the problem of multi-band stability, the article studies the influence of the impedance of the converging line and the unit expansion method on the equivalent accuracy, and proposes four types of new energy station aggregation models, which achieve good stability in the face of disturbances. However, due to the large number of equivalent classifications, the control situation is more complicated, which is not conducive to practical engineering applications.

[0005] 2. Zhou Lin et al. published "Equivalence and overall parameter identification of multiple machines in wind farms based on comprehensive model aggregation and parameter identification" Electric Power Automation Equipment: 2022, 42(01): 124-132. The article proposes to find similar disturbed trajectories based on the dynamic time warping DTW (Dynamic Time Warping) method and establish clustering indicators to perform homogeneous grouping of wind turbines. The DTW method enhances the morphological matching effect between multiple disturbed trajectory sequences by bending the time axis. Applying it to wind turbine grouping can overcome the problem of similarity distortion caused by factors such as fluctuations and mutations of disturbed trajectories, help search for disturbed trajectories with high similarity, and improve grouping accuracy. However, its algorithm is also relatively complex and focuses on high and low voltage ride-through problems, not frequency modulation response.

[0006] 3. Guo Mengjie et al. published "Accuracy Analysis and Evaluation of Sub- / Super-Synchronous Oscillation Mode Characteristics of Single-Unit Equivalent Model of Direct-Drive Wind Farm", Power System and Clean Energy: 2024, 40(09): 105-113. This article studies the characteristic performance of small disturbance oscillation mode before and after the equivalent of a single unit in a wind farm. First, a full-order state space model of a grid-connected direct-drive wind farm and a single-unit equivalent model based on the ROMC method and capacity weighted method are established. An evaluation method for the accuracy of sub- / super-synchronous oscillation mode before and after the equivalent of the system is proposed, and the validity of the criterion is verified. It is only used as a reference for the reliability of the equivalent.

[0007] In summary, the existing wind farm modeling methods mostly follow the multi-machine equivalent modeling in the direction of fitting the detailed model as much as possible, or only consider one aspect of the high and low voltage ride-through of the wind farm equivalent modeling, and do not take into account the different simulation needs in actual engineering practice. Especially in the field of station-level frequency regulation of wind power plants, although the model structure constructed by the traditional single-machine equivalent method is simple, it is only applicable to wind farms with similar working points of wind turbines and small wind speed differences. With the large-scale development of wind farms, considering the differences in frequency regulation control parameters and state quantities such as wind speed, the simulation accuracy of the traditional single-machine equivalent method is much different from that of detailed modeling, and has certain limitations. If the clustering characteristics of the frequency regulation response are considered, the direct accuracy improvement of the equivalent modeling method through intelligent optimization algorithms or complex physical process derivation will make the established model lack of universality and the parameter acquisition process of the equivalent machine is relatively complicated, and the engineering practice is poor. For this reason, there is an urgent need for a wind farm equivalent modeling method that is oriented to frequency regulation response analysis, has high accuracy and is easy to implement, to support the diversified simulation needs of large new energy power grids. Summary of the invention

[0008] The present invention aims to solve the problem that the traditional wind farm equivalent modeling method for frequency modulation response analysis in current practical projects cannot adapt to the frequency modulation response analysis scenario, resulting in distortion of the system frequency response characteristic analysis results when new energy participates in frequency modulation.

[0009] An improved single-machine equivalent method for wind farms for frequency modulation response analysis includes:

[0010] Obtain the topology, electrical equipment parameters and operation scenarios of the wind farm; construct a general frequency regulation control model for wind turbines; Based on the obtained wind farm topology, electrical equipment parameters and operation scenarios, a general frequency regulation control model for wind turbines is constructed, and a detailed electromagnetic transient model of the wind farm is established;

[0011] Based on the detailed electromagnetic transient model of the wind farm, according to the steady-state active output threshold T p Divide the wind turbines into two groups, with steady-state power less than or equal to T p The wind turbines that do not participate in frequency regulation are recorded as cluster 1, and the steady-state power is greater than T p The wind turbines participating in the frequency regulation are recorded as cluster 2. The actual frequency regulation power is calculated based on the wind turbines actually participating in the frequency regulation to correct the frequency regulation parameters of the equivalent machines, thereby achieving single-machine equivalence.

[0012] Furthermore, the universal frequency regulation control model of the wind turbine generator system includes three universal frequency regulation control modules: a virtual inertia control module, a droop control module and an overspeed load reduction control module.

[0013] Furthermore, the actual frequency modulation power is calculated based on the wind turbines actually participating in the frequency modulation, and the total steady-state active power of the wind turbines participating in the frequency modulation of the wind farm is calculated in the process of correcting the frequency modulation parameters of the equivalent machine. for:

[0014]

[0015] in, It is the active power output of the jth wind turbine in wind power cluster 2.

[0016] Furthermore, the process of achieving single-machine equivalence includes:

[0017] Total steady-state active power of single machine equivalent model participating in frequency regulation for:

[0018]

[0019] Capacity S of the single machine equivalent model eq for:

[0020]

[0021] Where: are the rated capacities of the i-th and j-th wind turbines in wind power clusters 1 and 2, respectively. and They are the total capacities of wind power clusters 1 and 2 respectively.

[0022] Furthermore, in the process of correcting the frequency modulation parameters of the equal value machine, the following control method is adopted:

[0023] During steady-state operation, the wind turbine controls the wind turbine operating point according to the overspeed load reduction reserve rate η:

[0024]

[0025] In the formula, k opt is the wind turbine maximum power tracking zone coefficient, k1 is the constant speed zone coefficient, η is the wind turbine load reduction coefficient; ω r is the rotor speed of the wind turbine, ω0, ω1, and ω2 are the starting speed, the cut-in speed in the constant speed zone, and the cut-in speed in the constant power zone, respectively; when the wind turbine speed is at [0, ω0], the wind turbine output power is 0, ω1 is the cut-in speed in the constant speed zone, and when the wind turbine speed is at [ω0, ω1], the wind turbine is in the overspeed load reduction control zone, and the wind turbine output power is When the wind turbine speed is between [ω1,ω max ], the wind turbine is in the constant speed zone, and the output power of the wind turbine is (1-η){k1(ω r -ω max )+P max}, when the wind turbine speed is greater than the maximum speed of the wind turbine ω max When the wind turbine runs at constant power, the output power is (1-η)P max ;

[0026] When the power system frequency drops, virtual inertia control and droop control will increase active power output to support the system frequency until a new balance is reached between the power required by the system and the output power of the wind turbines. Conversely, when the power system frequency rises, the wind turbines will reduce their active power output and continue to participate in frequency regulation.

[0027] Furthermore, during the control process of virtual inertia control, the virtual inertia coefficient of the single machine equivalent model is:

[0028]

[0029] In the formula, K vi is the virtual inertia coefficient, The virtual inertia coefficient of the single-machine equivalent model after the frequency regulation parameters of the equivalent machine are corrected in order to calculate the actual frequency regulation power based on the wind turbines actually participating in the frequency regulation; P total is the steady-state active power of the wind turbines in the wind farm.

[0030] Furthermore, during the droop control process, the droop coefficient of the single machine equivalent model is:

[0031]

[0032] In the formula, K dr is the virtual inertia coefficient, In order to calculate the actual frequency regulation power based on the wind turbines actually participating in the frequency regulation, the droop coefficient of the single-machine equivalent model after the frequency regulation parameters of the equivalent machine are corrected is realized.

[0033] An improved single-machine equivalent system for wind farms for frequency modulation response analysis, comprising at least a detailed electromagnetic transient model unit for wind farms and an improved single-machine equivalent unit for wind farms;

[0034] The wind farm detailed electromagnetic transient model unit: establishes a detailed electromagnetic transient model of the wind farm according to the acquired wind farm topology, electrical equipment parameters and operation scenarios and the general frequency modulation control model of the wind turbine generator set;

[0035] Improved single-machine equivalent unit of wind farm: Based on the detailed electromagnetic transient model of the wind farm, according to the steady-state active output threshold T p Divide the wind turbines into two groups, with steady-state power less than or equal to T p The wind turbines that do not participate in frequency regulation are recorded as cluster 1, and the steady-state power is greater than T p The wind turbines participating in the frequency regulation are recorded as cluster 2. The actual frequency regulation power is calculated based on the wind turbines actually participating in the frequency regulation to correct the frequency regulation parameters of the equivalent machines, thereby achieving single-machine equivalence.

[0036] Furthermore, the actual frequency modulation power is calculated based on the wind turbines actually participating in the frequency modulation, and the total steady-state active power of the wind turbines participating in the frequency modulation of the wind farm is calculated in the process of correcting the frequency modulation parameters of the equivalent machine. for:

[0037]

[0038] in, It is the active power output of the jth wind turbine in wind power cluster 2.

[0039] Furthermore, the process of achieving single-machine equivalence includes:

[0040] Total steady-state active power of single machine equivalent model participating in frequency regulation for:

[0041]

[0042] Capacity S of the single machine equivalent model eq for:

[0043]

[0044] Where: are the rated capacities of the i-th and j-th wind turbines in wind power clusters 1 and 2, respectively. and They are the total capacities of wind power clusters 1 and 2 respectively.

[0045] Beneficial effects of the present invention:

[0046] For wind farm modeling, an improved single-machine equivalent method and system for wind farm frequency response analysis is proposed. The adopted grouping method and improved equivalent parameter calculation method are relatively simple and easy to implement in engineering. They can not only adapt to the frequency response analysis scenario, but also significantly improve the frequency response accuracy of the wind farm single-machine equivalent model during frequency disturbances, thereby improving the simulation accuracy of the power grid, avoiding the problem of overly aggressive operation due to inaccurate wind farm equivalent models, and improving the safe operation level of the power grid and the wind power generation acceptance capacity. At the same time, the improved equivalent modeling idea provided by this method has strong versatility and can be applied to transient modeling of various types of new energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Improved single-machine equivalent modeling flow chart for wind farms oriented to frequency response analysis;

[0048] Figure 2 Improved single-machine equivalent model control structure diagram for wind farms oriented to frequency regulation response analysis;

[0049] Figure 3 It is the frequency modulation response curve of wind turbines under different wind speeds;

[0050] Figure 4 The figure shows the grouping of wind turbine components according to their active output.

[0051] Figure 5 The topological structure diagram of a wind farm is shown in the example;

[0052] Figure 6 This is a structural diagram of the improved single-machine equivalent model of a wind farm according to the present invention. DETAILED DESCRIPTION Specific implementation method one:

[0054] This implementation method is an improved single-machine equivalent method for wind farms for frequency modulation response analysis. Figure 1 The flowchart of wind farm improved single-machine equivalent modeling for frequency modulation response analysis is shown to illustrate the equivalent method. The wind farm improved single-machine equivalent method for frequency modulation response analysis described in this embodiment includes the following steps:

[0055] S1. Obtain the topological structure, electrical equipment parameters and operation scenarios of the wind farm;

[0056] The electrical equipment parameters of the wind farm include basic parameters of wind turbines, box transformer parameters, main transformer parameters and collector line network parameters; the operation scenario of the wind farm is the specific active power output of the wind turbines.

[0057] S2, constructing a universal frequency regulation control model for wind turbines, where each type of wind turbine shares a set of universal frequency regulation control model parameters;

[0058] The general frequency regulation control model of the wind turbine generator set includes three general frequency regulation control modules: virtual inertia control module Flag 1, droop control module Flag 2 and overspeed load reduction control module Flag 3; each module controls the enablement and disablement of the module through the state of the flag bit;

[0059] The virtual inertia control module Flag 1: controls the active power output of the wind turbine according to the frequency change rate of the power grid system:

[0060]

[0061] In the formula, ΔP vi is the active power regulation output by virtual inertia control, f is the system frequency, K vi is the virtual inertia control coefficient, t is the time, d represents the derivative, and P0 is the active power of the wind turbine in steady-state operation;

[0062] Virtual inertia control is designed to provide an inertial response similar to that of a traditional synchronous generator. By simulating the inertial characteristics of a synchronous machine, in a power grid dominated by renewable energy generation, when the grid frequency changes, virtual inertia control can quickly adjust the power output of the wind turbine to counteract frequency fluctuations.

[0063] The droop control module Flag 2: controls the active power output of the wind turbine according to the frequency deviation of the power grid system:

[0064] ΔP dr =-K dr ΔfP0 (13)

[0065] In the formula, ΔP dr K is the active power regulation of the droop control output. dr is the droop control coefficient; Δf is the deviation between the system frequency and the power frequency, t is the time, d represents the derivative, and P0 is the active power of the wind turbine in steady-state operation;

[0066] Droop control is achieved by adjusting the relationship between the active power output of the wind turbine and the grid frequency. Also similar to traditional generators, droop control (also known as frequency droop control) is mainly used to maintain the frequency stability of the grid. When the grid frequency drops, droop control increases the active power output of the wind turbine to help increase the frequency; conversely, when the grid frequency rises, it reduces the output power.

[0067] The overspeed load reduction control module Flag 3: controls the wind turbine operating point according to the overspeed load reduction reserve rate η:

[0068]

[0069] In the formula, k opt is the wind turbine maximum power tracking coefficient, k1 is the constant speed coefficient, and η is the wind turbine load reduction coefficient. r is the rotor speed of the wind turbine, ω0, ω1, and ω2 are the starting speed, the cut-in speed in the constant speed zone, and the cut-in speed in the constant power zone, respectively. When the wind turbine speed is at [0, ω0], the wind turbine output power is 0, ω1 is the cut-in speed in the constant speed zone, and when the wind turbine speed is at [ω0, ω1], the wind turbine is in the overspeed load reduction control zone, and the wind turbine output power is When the wind turbine speed is between [ω1,ω max ], the wind turbine is in the constant speed zone, and the output power of the wind turbine is (1-η){k1(ω r -ω max )+P max}, when the wind turbine speed is greater than the maximum speed of the wind turbine ω max When the wind turbine runs at constant power, the output power is (1-η)P max ;

[0070] In this method, each type of wind turbine shares a set of frequency control model parameters, such as Figure 2 In the three frequency modulation control modules shown, each module controls the enablement and disablement of the module through the status of the flag bit:

[0071] The states of the flag bit include "1" and "0". The "0" state represents disabling the control module, and the flag bit being in the "1" state represents enabling the control module.

[0072] The general frequency regulation control model flag of the wind turbine with virtual inertia control module Flag 1 = 1;

[0073] The general frequency regulation control model flag of the wind turbine without virtual inertia control module Flag 1 = 0;

[0074] The general frequency regulation control model flag of the wind turbine with droop control module Flag 2 = 1;

[0075] The general frequency regulation control model flag Flag 2 of the wind turbine without droop control module is 0;

[0076] The general frequency regulation control model flag of the wind turbine with overspeed load reduction control module Flag 3 = 1;

[0077] The general frequency regulation control model flag Flag 3 of the wind turbine generator set without overspeed load reduction control module is 0.

[0078] S3, construct a general frequency regulation control model of wind turbines based on the wind farm topology, electrical equipment parameters and operation scenarios obtained in S1 and S2, and establish a detailed electromagnetic transient model of the wind farm;

[0079] S4. Divide the wind turbines into two groups according to whether they participate in frequency regulation, and calibrate the frequency regulation power of the equivalent units:

[0080] The traditional single-machine equivalent approach takes the total steady-state active power of wind turbines in a wind farm as the reference quantity for frequency modulation power, and calculates frequency modulation control parameters such as virtual inertia control and droop control of the equivalent machine. When the wind speed range of the wind farm mainly covers high steady-state active power, the frequency modulation response error of the equivalent machine is acceptable. However, considering that the wind speed range of the actual wind farm is wider or mainly in low steady-state active power, the frequency modulation response of the traditional single-machine equivalent machine has a larger error than the detailed model, which is difficult to meet the simulation analysis requirements. Therefore, the steady-state power (steady-state active output) threshold T is first used. p The wind turbines are divided into two groups for the split point, and the actual frequency regulation power is calculated. In this process, the total steady-state active power of the wind power cluster that does not participate in the system frequency regulation is excluded from the total power of the wind turbines participating in the frequency regulation to avoid the problem of over-prediction of the frequency regulation capacity of the equivalent machine in the traditional wind farm single machine equivalent method. The improved virtual inertia coefficient and droop coefficient of the equivalent machine are calculated through the corrected frequency regulation power.

[0081] According to the steady-state power threshold T p The process of dividing the wind turbine group into two groups and calculating the actual frequency regulation power includes:

[0082] In order to meet the needs of frequency modulation response analysis, the steady-state power threshold T p is the split point, T p The selection is determined by the wind turbine model, which is the manufacturer's set parameter. The steady-state power is less than or equal to T p When the unit participates in frequency modulation, its rotor kinetic energy is small and there is no power reserve. If it participates in frequency modulation and generates active power, it is very easy to stall and disconnect from the grid. Therefore, it cannot participate in frequency modulation. Figure 4 As shown; suppose that there are n wind turbines in the wind power cluster (named as cluster 1), and the steady-state power is greater than T pThe wind turbines in this wind farm cluster have a total of m wind turbines (named as cluster 2), so the steady-state active power P of the wind turbines in the wind farm is total for:

[0083]

[0084] Where n and m are the total number of wind turbine clusters 1 and 2 respectively, P i NFR , are the active outputs of the i-th and j-th wind turbines in wind power clusters 1 and 2 respectively (i=1, 2, ..., n; j=1, 2, ..., m), and are the total steady-state active powers of wind power clusters 1 and 2 respectively.

[0085] By accurately analyzing and calculating the frequency regulation power of the wind farm, the total steady-state active power of the wind power cluster that does not participate in the system frequency regulation is excluded from the total power of the wind turbines participating in the frequency regulation to avoid the problem of over-prediction of the frequency regulation capacity of the equivalent machine in the traditional wind farm single machine equivalent method. for:

[0086]

[0087] Taking the total active power of the system participating in frequency regulation before and after the equivalent as the invariant, on the basis of the original traditional equivalent machine parameters, the frequency regulation parameters in the traditional single-machine equivalent model are corrected according to the ratio of the total steady-state active power of the wind turbines that can participate in system frequency regulation to the total steady-state active power of all wind turbines. Compared with the traditional single-machine equivalent method, its frequency regulation response is closer to the detailed electromagnetic transient model, so the total steady-state active power participating in frequency regulation of the improved single-machine equivalent model is for:

[0088]

[0089] The process of correcting the frequency regulation parameters in the traditional single-machine equivalent model according to the ratio of the total steady-state active power of the wind turbines that can participate in the system frequency regulation to the total steady-state active power of all wind turbines includes the following steps:

[0090] First, calculate the improved virtual inertia coefficient and droop coefficient of the equivalent machine:

[0091] Improved single-machine equivalent model control structure of wind farm for frequency modulation response analysis Figure 2 As shown, the wind turbines that can participate in frequency regulation operate under overspeed load reduction control in steady state. When the system frequency is disturbed, the process of coordinating virtual inertia control and droop control to participate in system frequency regulation includes:

[0092] During steady-state operation, the wind turbine controls the wind turbine operating point according to the overspeed load reduction reserve rate η:

[0093]

[0094] In the formula, k opt is the wind turbine maximum power tracking coefficient, k1 is the constant speed coefficient, and η is the wind turbine load reduction coefficient. r is the rotor speed of the wind turbine, ω0, ω1, and ω2 are the starting speed, the cut-in speed in the constant speed zone, and the cut-in speed in the constant power zone, respectively. When the wind turbine speed is at [0, ω0], the wind turbine output power is 0, ω1 is the cut-in speed in the constant speed zone, and when the wind turbine speed is at [ω0, ω1], the wind turbine is in the overspeed load reduction control zone, and the wind turbine output power is When the wind turbine speed is between [ω1,ω max ], the wind turbine is in the constant speed zone, and the output power of the wind turbine is (1-η){k1(ω r -ω max )+P max}, when the wind turbine speed is greater than the maximum speed of the wind turbine ω max When the wind turbine runs at constant power, the output power is (1-η)P max ;

[0095] When the system frequency drops, virtual inertia control and droop control will increase the active power output to support the system frequency until the power required by the system and the output power of the wind turbine reach a new balance; conversely, when the system frequency rises, the wind turbine will reduce its active power output and continue to participate in frequency regulation.

[0096] Virtual inertia frequency modulation power ΔP of detailed electromagnetic transient model of wind farm detail_vi for:

[0097]

[0098] In the formula, K vi is the virtual inertia coefficient, f is the system frequency, t is the time, and d represents the derivative.

[0099] After the equivalent value, the virtual inertia frequency modulation power of the improved single-machine equivalent model remains unchanged, then ΔP detail_vi It can also be expressed as:

[0100]

[0101] Where: It is the virtual inertia coefficient of the improved single-machine equivalent model after correction.

[0102] By combining equations (19) and (20), we can obtain the corrected virtual inertia coefficient of the improved single-machine equivalent model: for:

[0103]

[0104] Similarly, the droop frequency modulation power ΔP of the detailed electromagnetic transient model of the wind farm detail_dr for:

[0105]

[0106] In the formula, K dr is the virtual inertia coefficient, and Δf is the deviation between the system frequency and the power frequency.

[0107] After the equivalent value, the droop frequency modulation power of the improved single-machine equivalent model remains unchanged, and can be expressed as:

[0108]

[0109] Where: Corrected droop coefficient of the improved single-machine equivalent model.

[0110] By combining equations (22) and (23), the corrected improved single-machine equivalent model droop coefficient is obtained:

[0111]

[0112] Furthermore, based on the traditional single-machine equivalent method, the capacity S of the improved single-machine equivalent model is obtained. eq for:

[0113]

[0114] Where: are the rated capacities of the i-th and j-th wind turbines in wind power clusters 1 and 2, respectively (i=1, 2, ..., n; j=1, 2, ..., m), and They are the total capacities of wind power clusters 1 and 2 respectively.

[0115] It should be noted that Figure 5 and Figure 6 The detailed wind farm model and equivalent model shown in the figure are only examples. In actual application, a corresponding wind farm model needs to be established according to the actual situation of the wind farm to be modeled.

[0116] The present invention proposes an improved single-machine equivalent method and system for wind farm modeling for frequency modulation response analysis. The adopted grouping method and improved equivalent parameter calculation method are relatively simple and easy to implement in engineering. The frequency modulation response accuracy of the wind farm single-machine equivalent model during frequency disturbance is significantly improved, thereby improving the simulation accuracy of the power grid, avoiding the problem of overly aggressive operation due to inaccurate wind farm equivalent model, and improving the safe operation level of the power grid and the wind power generation acceptance capacity. At the same time, the improved equivalent modeling idea provided by the method has strong versatility and can be applied to transient modeling of various types of new energy.

[0117] Example

[0118] based on Figure 2 A detailed transient model of a wind farm is established, and the following test scenarios are designed to analyze the frequency regulation characteristics. The frequency regulation response curves of wind turbines at different wind speed operating points are as follows: Figure 3 As shown:

[0119] Test scenario 1 and scenario 2: The frequency is stepped down and up to 49.5Hz and 50.5Hz respectively, and then restored to 50Hz after 5s; the wind speed is from 3m / s at the beginning to 22m / s at the end, and the power interval is 0.01pu. The test results of the frequency step down and up are as follows: Figure 3 As shown in (a) and (b) in .

[0120] Test scenario 3 and scenario 4: The frequency decreases and increases at a rate of 0.5Hz / s, reaches 49.5Hz and 50.5Hz, and then maintains for 5s, and then recovers to 50Hz at the opposite rate. The wind speed scenario is the same as test scenario 1 and 2. The test results of the frequency slope decrease and increase are as follows: Figure 3 As shown in (c) and (d) in .

[0121] It can be seen that the active power response curves of wind turbines at different steady-state operating points under the same frequency disturbance are significantly different. The operating point is at the steady-state power threshold T p The wind turbines on both sides have different control modes and their frequency response characteristics are significantly different, and each exhibits obvious clustering characteristics. Steady-state power is less than or equal to T p The wind turbines do not participate in frequency modulation, and the steady-state power is greater than T p The wind turbines can stably increase the active power and have similar frequency regulation response characteristics.

[0122] Specific implementation method 2: This implementation method is a wind farm improved single-machine equivalent system for frequency modulation response analysis, which is actually a computer program that implements a wind farm improved single-machine equivalent method for frequency modulation response analysis. The wind farm improved single-machine equivalent system for frequency modulation response analysis described in this implementation method at least includes a wind farm detailed electromagnetic transient model unit and a wind farm improved single-machine equivalent unit;

[0123] The wind farm detailed electromagnetic transient model unit: establishes a detailed electromagnetic transient model of the wind farm according to the acquired wind farm topology, electrical equipment parameters and operation scenarios and the general frequency modulation control model of the wind turbine generator set;

[0124] Improved single-machine equivalent unit of wind farm: Based on the detailed electromagnetic transient model of the wind farm, according to the steady-state active output threshold T p Divide the wind turbines into two groups, with steady-state power less than or equal to T p The wind turbines that do not participate in frequency regulation are recorded as cluster 1, and the steady-state power is greater than T p The wind turbines participating in the frequency regulation are recorded as cluster 2. The actual frequency regulation power is calculated based on the wind turbines actually participating in the frequency regulation to correct the frequency regulation parameters of the equivalent machines, thereby achieving single-machine equivalence.

[0125] The actual frequency modulation power is calculated based on the wind turbines actually participating in the frequency modulation, and the total steady-state active power of the wind turbines participating in the frequency modulation of the wind farm is calculated in the process of correcting the frequency modulation parameters of the equivalent machine. for:

[0126]

[0127] in, It is the active power output of the jth wind turbine in wind power cluster 2.

[0128] The process of achieving single-machine equivalence includes:

[0129] Total steady-state active power of single machine equivalent model participating in frequency regulation for:

[0130]

[0131] Capacity S of the single machine equivalent model eq for:

[0132]

[0133] Where: are the rated capacities of the i-th and j-th wind turbines in wind power clusters 1 and 2, respectively. and They are the total capacities of wind power clusters 1 and 2 respectively.

[0134] The system may be run in a device including a processor and a memory, wherein the memory stores at least one instruction, and the at least one instruction is loaded by the processor to run the system.

[0135] Those skilled in the art will appreciate that at least one instruction stored is a computer program product corresponding to the method or system. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The scheme in the embodiment of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0136] The present application is described with reference to the flowcharts and / or block diagrams of the methods, systems, and computer program products according to the embodiments of the present application, and may also be used for corresponding devices. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0137] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0138] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0139] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0140] The above only describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the above specific implementation methods. Although the present invention has been disclosed as above in the preferred embodiments, it is not used to limit the present invention. Any technician familiar with the profession can make some changes or modify the technical contents disclosed above into equivalent embodiments with equivalent changes without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. An improved single-machine equivalent method for wind farms for frequency modulation response analysis, characterized in that: include: Obtain the topology, electrical equipment parameters and operation scenarios of the wind farm; Construct a general frequency control model for wind turbines; Based on the acquired wind farm topology, electrical equipment parameters and operation scenarios, construct a general frequency control model for wind turbines and establish a detailed electromagnetic transient model of the wind farm; Based on the detailed electromagnetic transient model of the wind farm, according to the steady-state active output threshold T p Divide the wind turbines into two groups, with steady-state power less than or equal to T p The wind turbines that do not participate in frequency regulation are recorded as cluster 1, and the steady-state power is greater than T p The wind turbines participating in the frequency regulation are recorded as cluster 2. The actual frequency regulation power is calculated based on the wind turbines actually participating in the frequency regulation to correct the frequency regulation parameters of the equivalent machines, thereby achieving single-machine equivalence.

2. The improved single-machine equivalent method for wind farm frequency modulation response analysis according to claim 1 is characterized in that: The general frequency regulation control model of the wind turbine generator set includes three general frequency regulation control modules: a virtual inertia control module, a droop control module and an overspeed load reduction control module.

3. The improved single-machine equivalent method for wind farms for frequency modulation response analysis according to claim 2 is characterized in that: The actual frequency modulation power is calculated based on the wind turbines actually participating in the frequency modulation, and the total steady-state active power of the wind turbines participating in the frequency modulation of the wind farm is calculated in the process of correcting the frequency modulation parameters of the equivalent machine. for: in, It is the active power output of the jth wind turbine in wind power cluster 2.

4. The improved single-machine equivalent method for wind farm frequency modulation response analysis according to claim 3 is characterized in that: The process of achieving single-machine equivalence includes: Total steady-state active power of single machine equivalent model participating in frequency regulation for: Capacity S of the single machine equivalent model eq for: Where: are the rated capacities of the i-th and j-th wind turbines in wind power clusters 1 and 2, respectively. and They are the total capacities of wind power clusters 1 and 2 respectively.

5. The improved single-machine equivalent method for wind farms for frequency modulation response analysis according to any one of claims 1 to 4, characterized in that: In the process of correcting the frequency modulation parameters of the equal value machine, the following control methods are adopted: During steady-state operation, the wind turbine controls the wind turbine operating point according to the overspeed load reduction reserve rate η: In the formula, k opt is the wind turbine maximum power tracking zone coefficient, k1 is the constant speed zone coefficient, η is the wind turbine load reduction coefficient; ω r is the rotor speed of the wind turbine, ω0, ω1, and ω2 are the starting speed, the cut-in speed in the constant speed zone, and the cut-in speed in the constant power zone, respectively; when the wind turbine speed is at [0, ω0], the wind turbine output power is 0, ω1 is the cut-in speed in the constant speed zone, and when the wind turbine speed is at [ω0, ω1], the wind turbine is in the overspeed load reduction control zone, and the wind turbine output power is When the wind turbine speed is between [ω1,ω max ], the wind turbine is in the constant speed zone, and the output power of the wind turbine is (1-η){k1(ω r -ω max )+P max }, when the wind turbine speed is greater than the maximum speed of the wind turbine ω max When the wind turbine runs at constant power, the output power is (1-η)P max ; When the power system frequency drops, virtual inertia control and droop control will increase active power output to support the system frequency until a new balance is reached between the power required by the system and the output power of the wind turbines. Conversely, when the power system frequency rises, the wind turbines will reduce their active power output and continue to participate in frequency regulation.

6. The improved single-machine equivalent method for wind farm frequency modulation response analysis according to claim 5 is characterized in that: During the virtual inertia control process, the virtual inertia coefficient of the single machine equivalent model is: In the formula, K vi is the virtual inertia coefficient, K*vi is the virtual inertia coefficient of the single-machine equivalent model after the frequency regulation parameters of the equivalent machine are corrected by calculating the actual frequency regulation power based on the wind turbines actually participating in the frequency regulation; P total is the steady-state active power of the wind turbines in the wind farm.

7. The improved single-machine equivalent method for wind farms for frequency modulation response analysis according to claim 5 is characterized in that: During the droop control process, the droop coefficient of the single machine equivalent model is: In the formula, K dr is the virtual inertia coefficient, In order to calculate the actual frequency regulation power based on the wind turbines actually participating in the frequency regulation, the droop coefficient of the single-machine equivalent model after the frequency regulation parameters of the equivalent machine are corrected is realized.

8. An improved single-machine equivalent system for wind farms for frequency modulation response analysis, characterized in that: At least include wind farm detailed electromagnetic transient model unit and wind farm improved single machine equivalent unit; The wind farm detailed electromagnetic transient model unit: establishes a detailed electromagnetic transient model of the wind farm according to the acquired wind farm topology, electrical equipment parameters and operation scenarios and the general frequency modulation control model of the wind turbine generator set; Improved single-machine equivalent unit of wind farm: Based on the detailed electromagnetic transient model of the wind farm, according to the steady-state active output threshold T p Divide the wind turbines into two groups, with steady-state power less than or equal to T p The wind turbines that do not participate in frequency regulation are recorded as cluster 1, and the steady-state power is greater than T p The wind turbines participating in the frequency regulation are recorded as cluster 2. The actual frequency regulation power is calculated based on the wind turbines actually participating in the frequency regulation to correct the frequency regulation parameters of the equivalent machines, thereby achieving single-machine equivalence.

9. The wind farm improved single machine equivalent system for frequency modulation response analysis according to claim 8 is characterized in that: The actual frequency modulation power is calculated based on the wind turbines actually participating in the frequency modulation, and the total steady-state active power of the wind turbines participating in the frequency modulation of the wind farm is calculated in the process of correcting the frequency modulation parameters of the equivalent machine. for: in, It is the active power output of the jth wind turbine in wind power cluster 2.

10. The wind farm improved single machine equivalent system for frequency modulation response analysis according to claim 9, characterized in that: The process of achieving single-machine equivalence includes: Total steady-state active power of single machine equivalent model participating in frequency regulation for: Capacity S of the single machine equivalent model eq for: Where: are the rated capacities of the i-th and j-th wind turbines in wind power clusters 1 and 2, respectively. and They are the total capacities of wind power clusters 1 and 2 respectively.

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