Method and device for optimizing proportion of grid-connected system and grid-connection type wind turbine in wind farm

Abstract

The application belongs to the technical field of wind power generation, and specifically discloses a wind farm grid-connected system grid-following type and grid-forming type wind turbine proportion optimization method and device, which comprises the following steps: changing the initial proportion of the grid-forming type wind turbine, and changing the grid strength under the updated proportion; calculating the power flow distribution of each node of the wind farm grid-connected system under the updated proportion, determining that the grid-connected system does not reach the capacity threshold based on the power flow distribution; establishing a state space model of the grid-connected system, and judging whether the grid-connected system is small signal stable; under the condition of small signal stability, analyzing the stability margin of the grid-connected system based on the dominant modal eigenvalue, evaluating the adaptability of the wind farm to the change of the grid strength by using a discrete coefficient, and recording the discrete coefficient; cyclically performing analysis on all grid strengths and wind turbine proportions, obtaining the discrete coefficients under all proportions, and selecting the grid-forming type wind turbine proportion corresponding to the minimum discrete coefficient as the optimal proportion. The application can improve the operation stability of the wind farm configuration result.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wind power generation, and more particularly relates to a wind farm grid-connected system grid-following and grid-forming wind turbine proportion optimization method and device. BACKGROUND

[0002] With the accelerated construction of new power systems, large-scale new energy and energy storage converters, high-voltage direct current transmission and other power electronic devices are connected to the alternating current power grid, which leads to rapid reduction of system strength and inertia, weakening of frequency / voltage support capability, and intensification of power electronic device oscillation instability risk. The "double high" power system faces severe challenges in safe and stable operation.

[0003] Grid-forming wind turbines can be stably connected to weak alternating current power grids, have functions of rapid inertia and frequency support, rapid voltage support, on-grid and off-grid switching and black start, and can be used to cope with problems such as low inertia and weak grid strength of the system, and expand the stability boundary of high-proportion new energy systems. Replacing part of the grid-following wind turbines in the traditional wind farm with grid-forming wind turbines can improve the stable operation capability of the wind farm, but due to the problems of equipment damage, fault ride-through and strong interaction of grid-forming wind turbines, it is not appropriate to configure too many grid-forming wind turbines.

[0004] Therefore, under the development trend of new power systems, how to effectively evaluate the auxiliary support efficiency of grid-forming wind turbines on surrounding grid-following wind turbines, and how to verify and determine the minimum configuration proportion of grid-forming wind turbines to maintain the stable operation of the power system and optimize the operation efficiency of the power system, are key problems that need to be further studied and solved.

[0005] Therefore, the small signal stability analysis method in the prior art is widely used in the existing research on the proportion configuration of grid-forming wind turbines, which can effectively evaluate the influence of the change of the proportion of grid-forming wind turbines on the short-term dynamic response and stability of the system, and further optimize the proportion configuration of grid-forming wind turbines. However, these methods ignore the long-time capacity overrun problem of the converter caused by the demand for alternating current voltage support of weak power grids, which leads to the fact that the configuration results of the wind farm cannot meet the stable operation demand in actual operation, and poses a potential threat to the power system.

[0006] In summary, the technical problem of the present application is how to solve the problem of poor operation stability of the wind farm configuration results caused by the capacity overrun of the grid-forming wind turbine proportion configuration method. SUMMARY

[0007] In view of the defects of the prior art, the purpose of the present application is to provide a wind farm grid-connected system grid-following and grid-forming wind turbine proportion optimization method and device, which aims to solve the problem of poor operation stability of the wind farm configuration results caused by the capacity overrun of the grid-forming wind turbine proportion configuration method.

[0008] To achieve the above object, in a first aspect, the application provides a wind farm grid-connected system grid-connected type and grid-constructed type wind turbine proportion optimization method, comprising:

[0009] Change the initial proportion of grid-constructed type wind turbines, and change the grid strength under the updated proportion;

[0010] Calculate the power flow distribution of each node of the wind farm grid-connected system under the updated proportion, and determine that the grid-connected system does not reach the capacity threshold based on the power flow distribution;

[0011] Establish a state space model of the grid-connected system, and determine whether the grid-connected system is small signal stable based on the state space model;

[0012] In the case of small signal stability, analyze the stability margin of the grid-connected system based on the dominant modal characteristic value, evaluate the adaptability of the wind farm to the change of the grid strength by using the discrete coefficient, and record the discrete coefficient;

[0013] Cyclically analyze all grid strengths and wind turbine proportions to obtain the discrete coefficients under all proportions, and select the grid-constructed type wind turbine proportion corresponding to the minimum discrete coefficient as the optimal proportion.

[0014] Optionally, the calculation of the power flow distribution of each node of the wind farm grid-connected system under the updated proportion, and the determination that the grid-connected system does not reach the capacity threshold based on the power flow distribution, comprises:

[0015] Establish an equivalent circuit of the wind farm grid-connected system, and determine the node voltage equation of the equivalent circuit;

[0016] Based on the node voltage equation, calculate the power flow distribution of each node of the wind farm grid-connected system under different working conditions, and in the case that the power flow distribution has a solution, determine that the active power of all wind turbines does not exceed the power limit;

[0017] Determine that the reactive power per unit of the wind turbine is within a preset range by using the grid-connected guide, so as to determine that the grid-connected system does not reach the capacity threshold.

[0018] Optionally, the establishment of the equivalent circuit of the wind farm grid-connected system and the determination of the node voltage equation of the equivalent circuit comprises:

[0019] According to the power external characteristics of the grid-connected type wind turbine and the grid-constructed type wind turbine, the current source equivalent model and the impedance equivalent model of the wind turbine are constructed;

[0020] According to the current source equivalent model and the impedance equivalent model, the system topology is constructed, and the admittance matrix is determined based on the system topology and the position distribution of the wind turbine;

[0021] According to the outlet voltage of each wind turbine, a voltage matrix is constructed, and according to the output current of each wind turbine, a current matrix is constructed;

[0022] The node voltage equations are constructed based on the voltage matrix, current matrix, and admittance matrix.

[0023] Optionally, the method for establishing the state-space model includes:

[0024] Based on differential algebraic equations, a state-space model of the wind farm grid-connected system is established around the steady-state operating point:

[0025]

[0026] in, The rate of change of the state vector. For state vectors, For the input vector, The state space matrix, For the input matrix, For the output matrix, This is the transfer matrix.

[0027] Optionally, under the condition of small-signal stability, the stability margin of the grid-connected system is analyzed based on the dominant mode eigenvalues, and the adaptability of the wind farm to changes in grid intensity is evaluated using the coefficient of variation, including:

[0028] The grid strength is updated with a fixed step size, and the dominant mode characteristic values ​​of the wind farm grid-connected system under different grid strengths are selected and recorded based on the state space model.

[0029] The average real part of the dominant mode eigenvalues ​​is calculated based on the dominant mode eigenvalues ​​and the total number of grid strength changes to reflect the distance of the eigenvalues ​​contained in the dominant mode to the imaginary axis;

[0030] The standard deviation of the real part of the dominant mode eigenvalue is calculated based on the dominant mode eigenvalue, the total number of power grid intensity changes, and the average real part.

[0031] The dispersion of different dominant modes is normalized, and the dispersion coefficients are determined based on the standard deviation and the average real part.

[0032] The adaptability to changes in power grid strength is evaluated based on the aforementioned coefficient of variation.

[0033] Optionally, the stability of the small signal is determined based on the root locus of the state-space model.

[0034] Optionally, it also includes:

[0035] If the grid-connected system reaches the capacity threshold, or if the small signal of the wind farm grid-connected system is unstable, and the proportion of wind turbines in the grid configuration cannot meet the static stability requirements, it is necessary to directly determine whether all grid strength and wind turbine ratio analyses have been completed.

[0036] In a second aspect, the application further provides a wind farm grid-connected system grid-connected type and grid-constructed type wind turbine proportion optimization device, comprising:

[0037] A proportion updating module is configured to change the initial proportion of the grid-constructed type wind turbine and change the grid strength under the updated proportion.

[0038] A capacity judgment module is configured to calculate the power flow distribution of each node of the wind farm grid-connected system under the updated proportion, and determine that the grid-connected system does not reach the capacity threshold based on the power flow distribution.

[0039] A stability judgment module is configured to establish a state space model of the grid-connected system, and determine whether the grid-connected system is small signal stable based on the state space model.

[0040] An adaptability evaluation module is configured to, in the case of small signal stability, analyze the stability margin of the grid-connected system based on dominant modal eigenvalues, evaluate the adaptability of the wind farm to the change of the grid strength by using a discrete coefficient, and record the discrete coefficient.

[0041] An optimal selection module is configured to cyclically analyze all grid strengths and wind turbine proportions to obtain the discrete coefficients under all proportions, and select the proportion of the grid-constructed type wind turbine corresponding to the minimum discrete coefficient as the optimal proportion.

[0042] In a third aspect, the application provides an electronic device, comprising: at least one memory configured to store a program; and at least one processor configured to execute the program stored in the memory, wherein the processor is configured to execute the method described in the first aspect or any possible implementation manner of the first aspect.

[0043] In a fourth aspect, the application provides a computer-readable storage medium, which stores a computer program, and when the computer program is executed on a processor, the processor executes the method described in the first aspect or any possible implementation manner of the first aspect.

[0044] In a fifth aspect, the application provides a computer program product, which, when executed on a processor, causes the processor to execute the method described in the first aspect or any possible implementation manner of the first aspect.

[0045] It can be understood that the beneficial effects of the second aspect to the fifth aspect described above can be referred to the related description in the first aspect, and will not be repeated here.

[0046] Overall, compared with the prior art, the above technical solutions conceived by the application have the following beneficial effects:

[0047] (1) The wind farm grid-connected system grid-connected type and grid-constructed type wind turbine proportion optimization configuration method constructed by the application overcomes the configuration problem of grid-constructed type wind turbines under multiple constraint conditions, can systematically analyze the performance of the wind farm under different grid conditions, optimize the grid proportion of wind turbines, comprehensively consider the stability problem of the wind farm grid-connected system, and effectively improve the operation stability of the wind farm configuration result through optimization of the proportion of wind turbines, analysis of power flow distribution, establishment of a state space model, and evaluation of stability margin, thereby improving the safety of power system operation.

[0048] (2) The application constructs a typical paradigm in the future energy storage grid-connected field, which can promote the development of efficient, economical and reliable grid-connected technology and improve the economy and operation flexibility of the wind power grid-connected system.

[0049] (3) The wind farm grid-connected system grid-connected type and grid-constructed type wind turbine proportion optimization configuration method constructed by the application can make full use of the advantages of grid-constructed type wind turbines, improve the stability of the grid, ensure the continuous and reliable operation of the grid, reduce the economic loss caused by excessive configuration of grid-constructed type wind turbines, and is conducive to the large-scale development of new energy and the saving of energy costs. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 is one of the flowcharts of the wind farm grid-connected system grid-connected type and grid-constructed type wind turbine proportion optimization method provided by the embodiments of the application;

[0051] Figure 2 is the second flowchart of the wind farm grid-connected system grid-connected type and grid-constructed type wind turbine proportion optimization method provided by the embodiments of the application;

[0052] Figure 3 is the structural schematic diagram of the wind farm grid-connected system grid-connected type and grid-constructed type wind turbine proportion optimization device provided by the embodiments of the application;

[0053] Figure 4 is the structural schematic diagram of the electronic device provided by the embodiments of the application. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical scheme and advantages of the application more clear and explicit, the application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and do not limit the application.

[0055] The term "and / or" in this paper is a description of the association relationship between the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. The symbol " / " in this paper represents the relationship of or in the associated objects, for example, A / B represents A or B.

[0056] The terms "first" and "second" and the like in the description and claims of this application are used for distinguishing between similar elements and not necessarily for describing a specific sequential or chronological order. For instance, a first response message and a second response message are used for distinguishing between two different response messages and not necessarily for describing a specific sequential or chronological order.

[0057] In the embodiments of this application, the words "exemplary" and "for example" are used to mean serving as an example, instance, or illustration, at 99 least with respect to the specific embodiments described and not necessarily with respect to other embodiments. In other words, the words "exemplary" and "for example" are used to illustrate and to not to limit the scope of the disclosure. The words "exemplary" and "for example" must each be construed to reserve their ordinary meaning with respect to the specific embodiments described herein and not to limit or narrow the scope of the disclosure as a whole.

[0058] In the description of the embodiments of this application, unless otherwise specified, "plurality" means two or more, for example, a plurality of processing units means two or more processing units, and the like; a plurality of elements means two or more elements, and the like.

[0059] The embodiments of this application will be described below with reference to the accompanying drawings.

[0060] With reference to Figure 1 The application provides a wind farm grid-connected system grid-connected type and grid-constructed type wind turbine proportion optimization method, comprising:

[0061] S101. Change the initial proportion of the grid-constructed type wind turbine, and change the grid strength under the updated proportion;

[0062] S102. Calculate the power flow distribution of each node of the wind farm grid-connected system under the updated proportion, and determine that the grid-connected system does not reach the capacity threshold based on the power flow distribution;

[0063] S103. Establish a state space model of the grid-connected system, and judge whether the grid-connected system is small signal stable based on the state space model;

[0064] S104. In the case of small signal stability, analyze the stability margin of the grid-connected system based on the dominant modal characteristic value, evaluate the adaptability of the wind farm to the change of the grid strength by using the discrete coefficient, and record the discrete coefficient;

[0065] S105. Cycle the analysis of all grid strengths and wind turbine proportions to obtain the discrete coefficients under all proportions, and select the grid-constructed type wind turbine proportion corresponding to the minimum discrete coefficient as the optimal proportion.

[0066] Specifically, first, the initial proportion is changed by step S101, and the grid strength under the proportion is changed. Based on the actual grid operating conditions, different grid strengths are simulated or calculated. The purpose is to ensure that the initial grid-type wind turbine proportion can meet the basic power generation demand, and to improve the flexibility and adaptability of the system by dynamically adjusting the wind turbine proportion.

[0067] Secondly, the power flow distribution of each node of the wind farm grid-connected system under the updated proportion is calculated by step S102. The process of power flow calculation is to calculate the power distribution of the grid nodes under the updated proportion by the power flow analysis method, so as to identify the power flow characteristics and power distribution of each node in the grid-connected system.

[0068] According to the power flow calculation result, it is judged whether the system reaches or exceeds the capacity threshold. When the grid-connected system reaches the capacity threshold, it is determined that the grid-type wind turbine proportion cannot meet the static stability requirement, and it is directly judged whether all grid strengths and wind turbine proportions are analyzed.

[0069] Further, by step S103, the state space model of the grid-connected system is established, and the small signal stability of the system is judged. The state space model is established around the steady-state operating point using differential algebraic equations.

[0070] Based on the differential algebraic equation, the state space model of the wind farm grid-connected system is established around the steady-state operating point:

[0071]

[0072] wherein, is the rate of change of the state vector, is the state vector, is the input vector, is the state space matrix, is the input matrix, is the output matrix, is the transfer matrix.

[0073] The small signal stability analysis is performed by calculating the eigenvalues of the state matrix , and analyzing the real part to judge the small signal stability: if the real part of all eigenvalues is negative, the system is small signal stable. If there is an eigenvalue with a real part of zero or positive, the system is unstable.

[0074] When the small signal of the wind farm grid-connected system is unstable, it is determined that the grid-type wind turbine proportion cannot meet the static stability requirement, and it is directly judged whether all grid strengths and wind turbine proportions are analyzed.

[0075] By step S104, the stability margin is analyzed under the condition of small signal stability.

[0076] First, a dominant mode eigenvalue analysis is performed. In the case of small signal stability, the dominant eigenvalue of the system is calculated and its corresponding mode is determined. The dominant mode eigenvalue is used to estimate the stability margin of the system, which represents the ability of the system to resist disturbances. By calculating the dispersion coefficient, the adaptability of the wind farm to changes in grid strength is evaluated. In this embodiment, the dispersion coefficient is recorded and evaluated to optimize the response characteristics of the wind farm grid-connected system.

[0077] Finally, the analysis of all grid strengths and wind turbine ratios is performed through the S105 loop. For all possible combinations of grid strengths and wind turbine ratios, power flow calculation, state space modeling and small signal stability analysis are performed. In each iteration, the corresponding dispersion coefficient and the stability results under various combinations are recorded. By comparing the dispersion coefficients of all combinations, the wind turbine ratio corresponding to the minimum dispersion coefficient is selected as the optimal ratio to ensure that the system adapts to changing grid conditions to the greatest extent.

[0078] The embodiments of the present application find the optimal wind turbine ratio through comprehensive analysis to maximize the stability and efficiency of the wind farm in the grid-connected case.

[0079] Optionally, the calculation of the power flow distribution of each node of the wind farm grid-connected system under the updated ratio includes:

[0080] An equivalent circuit of the wind farm grid-connected system is established, and the node voltage equation of the equivalent circuit is determined;

[0081] Based on the node voltage equation, the power flow distribution of each node of the wind farm grid-connected system under different operating conditions is calculated, and in the case that the power flow distribution has a solution, it is determined that the active power of all wind turbines does not exceed the power limit;

[0082] The reactive power per unit of the wind turbine is determined to be within a predetermined range using the grid connection guidelines to determine that the capacity threshold of the grid-connected system has not been reached.

[0083] Further, the establishment of the equivalent circuit of the wind farm grid-connected system and the determination of the node voltage equation of the equivalent circuit include:

[0084] According to the power external characteristics of the grid-connected wind turbine and the grid-forming wind turbine, a current source equivalent model and an impedance equivalent model of the wind turbine are constructed;

[0085] According to the current source equivalent model and the impedance equivalent model, a system topology is constructed, and a admittance matrix is determined based on the system topology and the position distribution of the wind turbine;

[0086] According to the outlet voltage of each wind turbine, a voltage matrix is constructed, and according to the output current of each wind turbine, a current matrix is constructed;

[0087] The node voltage equations are constructed based on the voltage matrix, current matrix, and admittance matrix.

[0088] Specifically, in this embodiment, the proportion of grid-connected wind turbines in the wind farm is varied within the range of 0% to 100%, thus changing the grid strength. An equivalent circuit of the wind farm grid-connected system is established, and the node voltage equations of this circuit are written:

[0089]

[0090] in, U gi and I i Indicates the first in the wind farm i The typhoon turbine's outlet voltage and output current, and the admittance matrix Y, depend on the system parameters and are determined based on the current source equivalent model, impedance equivalent model, and the location of the wind turbine.

[0091] Furthermore, the power flow distribution of each node in the wind farm grid-connected system under different operating conditions is calculated to determine whether the grid-connected system has reached the capacity limit; the power flow distribution of the system is solved based on the node voltage equation. If the power flow has a solution, then the active power of all wind turbines will not exceed the power limit.

[0092] Given active power P For reference value P ref Further determine the per-unit value of reactive power for each wind turbine. Q To determine whether the limit has been reached, according to the grid connection guidelines, the per-unit value of the reactive power of the wind turbine should be within ±0.312 pu, i.e. Q min < Q < Q max , Q min =-0.312, Q max =0.312, at this point, the system meets the capacity limit.

[0093] Optionally, under the condition of small-signal stability, the stability margin of the grid-connected system is analyzed based on the dominant mode eigenvalues, and the adaptability of the wind farm to changes in grid intensity is evaluated using the coefficient of variation, including:

[0094] The grid strength is updated with a fixed step size, and the dominant mode characteristic values ​​of the wind farm grid-connected system under different grid strengths are selected and recorded based on the state space model.

[0095] The average real part of the dominant mode eigenvalues ​​is calculated based on the dominant mode eigenvalues ​​and the total number of grid strength changes to reflect the distance of the eigenvalues ​​contained in the dominant mode to the imaginary axis;

[0096] The standard deviation of the real part of the dominant mode eigenvalue is calculated based on the dominant mode eigenvalue, the total number of power grid intensity changes, and the average real part.

[0097] The dispersion of different dominant modes is normalized, and the dispersion coefficients are determined based on the standard deviation and the average real part.

[0098] The adaptability to changes in power grid strength is evaluated based on the aforementioned coefficient of variation.

[0099] Specifically, in this embodiment, if the small signal of the system is stable, the stability margin of the system is analyzed based on the characteristic value of the dominant mode of the system, and the discrete coefficients are designed to evaluate the adaptability of the system to changes in power grid intensity.

[0100] The dominant mode of the system is selected and recorded based on the root locus. y 1… y n To reflect the distances from the eigenvalues ​​contained in the dominant mode to the imaginary axis, it is necessary to calculate the average value of the real parts of the eigenvalues. μ :

[0101]

[0102] in, The grid strength changes in fixed steps to the th j Dominant mode eigenvalues ​​during step, n The total number of grid strength changes is represented by this distance, which affects the trend of system gain and phase margin changes. The farther the dominant mode is from the imaginary axis, the larger the phase margin and gain margin, and the lower the risk of system instability.

[0103] To measure the dispersion of the dominant mode as the power grid strength changes, the standard deviation of the real part of the dominant mode eigenvalues ​​is calculated. σ :

[0104]

[0105] The smaller the offset distance of the dominant mode when the grid intensity changes, the stronger the system's adaptability to changes in grid intensity.

[0106] Considering the variation of system state variables and dominant modes with the proportion of grid-type wind turbines, the dispersion of different dominant modes is normalized using the standard deviation. σ Compared with the average μ The ratio of the two factors is used to measure the relative degree of dispersion, i.e., the coefficient of dispersion.

[0107]

[0108] The smaller the value, the stronger the ability of the wind farm grid-connected system to maintain stable operation when the grid strength changes;

[0109] By comparing the different network configuration of wind turbine configuration , determine the minimum The corresponding network type wind turbine ratio is the optimal ratio.

[0110] Referring to Figure 2 , Figure 2 is the complete flowchart of the embodiment of the application, comprising the following steps:

[0111] Step 1: change the network type wind turbine ratio, and change the grid strength under the ratio, calculate the power flow distribution of each node of the wind farm grid-connected system;

[0112] Step 2: determine whether the grid-connected system reaches the capacity limit. If yes, the network type wind turbine ratio cannot meet the static stability requirement, further determine whether all grid strength and ratio analysis is completed; if not, proceed to step 3;

[0113] Step 3: establish the state space model of the grid-connected system, determine whether the system is small signal stable. If yes, record the dominant mode eigenvalue of the system under different grid strength, proceed to step 4; if not, determine whether all grid strength and ratio analysis is completed;

[0114] Step 4: based on the dominant mode eigenvalue analysis of the system stability margin, design the discrete coefficient to evaluate the adaptability of the wind farm to the change of grid strength, record the discrete coefficient;

[0115] Step 5: determine whether all grid strength and network type wind turbine ratio analysis is completed. If yes, proceed to step 6; if not, return to step 1;

[0116] Step 6: summarize the discrete coefficient under all the above ratios, select the network type wind turbine ratio corresponding to the minimum discrete coefficient as the optimal ratio.

[0117] Referring to Figure 3 , the application also provides a wind farm grid-connected system network type and network type wind turbine ratio optimization device, comprising:

[0118] The ratio updating module 310 is used for changing the initial ratio of the network type wind turbine, and changing the grid strength under the updated ratio;

[0119] The capacity determination module 320 is used for calculating the power flow distribution of each node of the wind farm grid-connected system under the updated ratio, and determining that the grid-connected system does not reach the capacity threshold based on the power flow distribution;

[0120] The stability determination module 330 is used for establishing the state space model of the grid-connected system, and determining whether the grid-connected system is small signal stable based on the state space model;

[0121] The adaptive evaluation module 340 is configured to analyze the stability margin of the grid-connected system based on the dominant modal eigenvalue in the case of small signal stability, evaluate the adaptability of the wind farm to the change of the grid strength by using the discrete coefficient, and record the discrete coefficient.

[0122] The optimal selection module 350 is configured to cyclically analyze all grid strengths and wind turbine proportions to obtain the discrete coefficients under all proportions, and select the proportion of the grid-connected wind turbine corresponding to the minimum discrete coefficient as the optimal proportion.

[0123] Optionally, the calculation of the power flow distribution of each node of the grid-connected system of the wind farm under the updated proportion includes:

[0124] An equivalent circuit of the grid-connected system of the wind farm is established, and a node voltage equation of the equivalent circuit is determined.

[0125] The power flow distribution of each node of the grid-connected system of the wind farm under different working conditions is calculated based on the node voltage equation, and it is determined that the active power of all wind turbines does not exceed the power limit in the case that the power flow distribution has a solution.

[0126] The reactive power standard value of the wind turbine is determined to be within a preset range by using the grid connection guide, so as to determine that the capacity threshold of the grid-connected system is not reached.

[0127] Optionally, the establishment of the equivalent circuit of the grid-connected system of the wind farm and the determination of the node voltage equation of the equivalent circuit include:

[0128] According to the power external characteristics of the grid-connected wind turbine and the grid-connected wind turbine, a current source equivalent model and an impedance equivalent model of the wind turbine are constructed;

[0129] The system topology is constructed according to the current source equivalent model and the impedance equivalent model, and the admittance matrix is determined based on the system topology and the position distribution of the wind turbine;

[0130] The voltage matrix is constructed according to the outlet voltage of each wind turbine, and the current matrix is constructed according to the output current of each wind turbine;

[0131] The node voltage equation is constructed based on the voltage matrix, the current matrix and the admittance matrix.

[0132] Optionally, the establishment method of the state space model includes:

[0133] Based on the differential algebraic equation, the state space model of the grid-connected system of the wind farm is established around the steady-state operating point:

[0134]

[0135] wherein, is the change rate of the state vector. is a state vector, is an input vector, is a state space matrix, is an input matrix, is an output matrix, is a transfer matrix.

[0136] Optionally, in the case of small signal stability, the stability margin of the grid-connected system is analyzed based on the dominant modal eigenvalue, and the adaptability of the wind farm to the change of the grid strength is evaluated using the dispersion coefficient, including:

[0137] The grid strength is updated at a fixed step, and the dominant modal eigenvalue of the wind farm grid-connected system under different grid strengths is selected and recorded based on the state space model;

[0138] According to the dominant modal eigenvalue, the total number of grid strength changes, the average value of the real part of the dominant modal eigenvalue is calculated to reflect the distance of the eigenvalue contained in the dominant mode to the imaginary axis;

[0139] Based on the dominant modal eigenvalue, the total number of grid strength changes, and the average value of the real part, the standard deviation of the real part of the dominant modal eigenvalue is calculated;

[0140] The dispersion degree of different dominant modes is normalized, and the dispersion coefficient is determined according to the standard deviation and the average value of the real part;

[0141] The adaptability of the grid strength change is evaluated based on the dispersion coefficient.

[0142] Optionally, the small signal stability is determined according to the root locus of the state space model.

[0143] Optionally, it also includes a direct judgment module for:

[0144] In the case that the grid-connected system reaches the capacity threshold, or the small signal of the wind farm grid-connected system is unstable, it is determined that the proportion of the grid-connected type wind turbine cannot meet the static stability requirement, and whether all grid strength and wind turbine proportion analysis is completed is directly determined.

[0145] It should be understood that the above device is used to execute the method in the above embodiment, and the corresponding program module in the device has similar implementation principles and technical effects to the description in the above method, and the working process of the device can refer to the corresponding process in the above method, which will not be repeated here.

[0146] Based on the method in the above embodiments, an electronic device is provided in the embodiments of the present application, which can include a processor 410, a communications interface 420, a memory 430 and a communications bus 440, wherein the processor 410, the communications interface 420 and the memory 430 complete communications with each other through the communications bus 440. The processor 410 can invoke the logical instructions in the memory 430 to execute the method in the above embodiments.

[0147] In addition, the logical instructions in the memory 430 described above can be implemented in the form of a software functional unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product in essence or the part that contributes to the prior art or part of the technical solutions, which is stored in a storage medium, includes a number of instructions to make a computer device (which can be a personal computer, a server or a network device, etc.) execute all or part of the steps of the method described in the embodiments of the present application.

[0148] Based on the method in the above embodiments, a computer readable storage medium is provided in the embodiments of the present application, which stores a computer program, when the computer program runs on a processor, makes the processor execute the method in the above embodiments.

[0149] Based on the method in the above embodiments, a computer program product is provided in the embodiments of the present application, when the computer program product runs on a processor, makes the processor execute the method in the above embodiments.

[0150] It can be understood that the processor in the embodiments of the present application can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general-purpose processor can be a microprocessor or any conventional processor.

[0151] The method steps in the embodiments of the present application can be implemented by means of hardware, or by means of a processor executing software instructions. The software instructions can be composed of corresponding software modules, which can be stored in a Random Access Memory (RAM), a flash memory, a Read-only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically EPROM (EEPROM), a register, a hard disk, a mobile hard disk, a CD-ROM, or any other form of storage medium well known in the art. An exemplary storage medium is coupled to a processor, such that the processor can read information from, and write information to, the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC.

[0152] In the above embodiments, all or some of the steps can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or some of the steps can be implemented by one or more computer programs. When implemented by computer programs, the computer programs can be stored in a computer readable storage medium, and executed by a processor. The computer readable storage medium can be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically EPROM (EEPROM), a register, a hard disk, a mobile hard disk, a CD-ROM, or any other form of storage medium well known in the art. The computer readable storage medium can be coupled to the processor, such that the processor can read information from, and write information to, the computer readable storage medium.

[0153] It can be understood that various numerical numbers involved in the embodiments of the present application are only used for differentiation for convenience of description, and are not used to limit the scope of the embodiments of the present application.

[0154] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A wind farm grid-connected system grid-connected type and grid-constructed type wind turbine proportion optimization method, characterized in that, The method comprises the following steps: changing the initial proportion of grid-connected wind turbines and changing the grid strength at the updated proportion; calculating the power flow distribution of each node of the wind farm grid-connected system at the updated proportion, and determining that the grid-connected system does not reach the capacity threshold based on the power flow distribution; establishing a state space model of the grid-connected system, and judging whether the grid-connected system is small signal stable based on the state space model; in the case of small signal stability, analyzing the stability margin of the grid-connected system based on the dominant modal eigenvalue, evaluating the adaptability of the wind farm to the change of the grid strength by using the discrete coefficient, and recording the discrete coefficient; all grid strengths and turbine proportions are analyzed in a loop to obtain the discrete coefficient at all proportions, and the grid-connected wind turbine proportion corresponding to the minimum discrete coefficient is selected as the optimal proportion.

2. The method of claim 1, wherein the method is a method of optimizing the proportion of grid-connected and grid-forming wind turbines in a wind farm grid integration system, characterized in that, The calculation of the power flow distribution of each node of the wind farm grid-connected system at the updated proportion, and the determination that the grid-connected system does not reach the capacity threshold based on the power flow distribution, comprises the following steps: establishing an equivalent circuit of the wind farm grid-connected system, and determining the node voltage equation of the equivalent circuit; based on the node voltage equation, calculating the power flow distribution of each node of the wind farm grid-connected system under different working conditions, and determining that the active power of all wind turbines does not exceed the power limit in the case that the power flow distribution has a solution; determining that the grid-connected system does not reach the capacity threshold by using the grid-connected guide to determine that the reactive power per unit of the wind turbine is within a preset range.

3. The method of claim 2, wherein the method further comprises: The establishment of the equivalent circuit of the wind farm grid-connected system and the determination of the node voltage equation of the equivalent circuit comprises the following steps: according to the power external characteristics of the grid-connected wind turbine and the grid-connected wind turbine, constructing the current source equivalent model and the impedance equivalent model of the wind turbine; constructing the system topology according to the current source equivalent model and the impedance equivalent model, and determining the admittance matrix based on the system topology and the position distribution of the wind turbine; constructing the voltage matrix according to the outlet voltage of each wind turbine, and constructing the current matrix according to the output current of each wind turbine; constructing the node voltage equation based on the voltage matrix, the current matrix and the admittance matrix.

4. The method of claim 1, wherein the method is a method of optimizing the ratio of grid-connected and grid-forming wind turbines in a wind farm grid integration system, characterized in that, The establishment method of the state space model comprises the following steps: based on the differential algebraic equation, establishing the state space model of the wind farm grid-connected system around the steady-state operating point: wherein, is the rate of change of the state vector, is the state vector, is the input vector, is the state space matrix, is the input matrix, is the output matrix, is the transfer matrix.

5. The method of claim 1, wherein, in the case of small signal stability, analyzing the stability margin of the grid-connected system based on the dominant modal eigenvalue, and evaluating the adaptability of the wind farm to the change of the grid strength by using the discrete coefficient, comprising: updating the grid strength at a fixed step, and selecting and recording the dominant modal eigenvalue of the wind farm grid-connected system under different grid strengths based on the state space model; according to the dominant modal eigenvalue, the total number of grid strength changes, and the average value of the real part of the dominant modal eigenvalue, the average value of the real part of the dominant modal eigenvalue is calculated to reflect the distance of the characteristic value contained in the dominant modal to the imaginary axis; based on the dominant modal eigenvalue, the total number of grid strength changes, and the average value of the real part, the standard deviation of the real part of the dominant modal eigenvalue is calculated; the discrete degree of different dominant modes is normalized, and the discrete coefficient is determined according to the standard deviation and the average value of the real part; the adaptability of the grid strength change is evaluated based on the discrete coefficient.

6. The method of claim 1, wherein, The small signal stability is judged according to the root locus of the state space model.

7. The method of claim 1, wherein, Further comprising: In the case that the grid-connected system reaches the capacity threshold or the small signal of the wind farm grid-connected system is unstable, it is determined that the proportion of the grid-connected wind turbine cannot meet the static stability requirement, and it is directly determined whether all grid strength and wind turbine proportion analysis is completed.

8. A wind farm grid-connected system grid-following and grid-forming wind turbine proportion optimization device, characterized in that, The method comprises the steps of: a proportion updating module, which is used to change the initial proportion of the grid-connected wind turbine and change the grid strength under the updated proportion; a capacity judging module, which is used to calculate the power flow distribution of each node of the wind farm grid-connected system under the updated proportion, and determine whether the grid-connected system reaches the capacity threshold based on the power flow distribution; a stability judging module, which is used to establish a state space model of the grid-connected system, and judge whether the grid-connected system is small signal stable based on the state space model; an adaptability evaluating module, which is used to analyze the stability margin of the grid-connected system based on the dominant modal eigenvalue in the case of small signal stability, evaluate the adaptability of the wind farm to the change of the grid strength by using the discrete coefficient, and record the discrete coefficient; an optimal selection module, which is used to cyclically analyze all grid strength and wind turbine proportion to obtain the discrete coefficient under all proportions, and select the proportion of the grid-connected wind turbine corresponding to the minimum discrete coefficient as the optimal proportion.

9. An electronic device, comprising: The method comprises the steps of: at least one memory for storing a computer program; at least one processor for executing the program stored in the memory, when the program stored in the memory is executed, the processor is used to execute the method as claimed in any one of claims 1-7.

10. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1-9. When the computer program runs on the processor, the processor executes the method as claimed in any one of claims 1-7.

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