Oscillation determination method and device for new energy station, electronic equipment and storage medium

Abstract

This application relates to the field of power system stability analysis technology, and particularly to a method, device, electronic equipment, and storage medium for determining oscillations in renewable energy power plants. The method includes: obtaining impedance models of target renewable energy units in a grid-connected renewable energy power plant under multiple preset operating conditions; based on the impedance models, outputting the impedance ratio matrix eigenvalues ​​of the target renewable energy units under each preset operating condition, and generating a Nyquist curve from the impedance ratio matrix eigenvalues ​​of the target renewable energy units under each preset operating condition; determining whether the grid-connected renewable energy power plant has an oscillation risk based on the Nyquist curve; and, when an oscillation risk exists, obtaining the oscillation result of the grid-connected renewable energy power plant based on a preset stability criterion and the network reactance matrix of the grid-connected renewable energy power plant. This solves the problem of unknown renewable energy unit models and parameters in practice, effectively reduces the computational load in the oscillation stability analysis of renewable energy power plants, and improves work efficiency.

Description

Technical Field

[0001] This application relates to the field of power system stability analysis technology, and in particular to a method, device, electronic equipment and storage medium for determining oscillations in new energy power plants. Background Technology

[0002] In recent years, new energy power generation, represented by wind power and photovoltaics, has been vigorously developed and widely applied globally. In the future, new energy power generation will undoubtedly see further development and application in my country. However, while large-scale grid connection of new energy sources alleviates the energy and environmental crisis, the complex dynamic coupling between the power electronic control of new energy units and the AC and DC power grids can easily trigger grid-connected system oscillations and instability. Oscillation problems caused by the connection of new energy power plants can range from large-scale grid disconnection of new energy units to affecting surrounding power grids, causing equipment tripping or even damage, seriously threatening the safe and stable operation of the power grid.

[0003] In related technologies, mode analysis and impedance analysis are commonly used methods for analyzing the oscillation stability of grid-connected renewable energy power plants. Mode analysis determines the stability of the system based on whether the eigenvalues ​​of the linearized state-space matrix of the grid-connected system are all located in the left half of the complex plane. Impedance analysis, on the other hand, is based on the system's frequency domain transfer function model and uses frequency domain stability analysis methods such as the Nyquist criterion and amplitude and phase margin criteria to determine the oscillation stability of the grid-connected system. Since the transfer function model takes current and voltage as inputs and outputs, it is called an impedance model.

[0004] However, linearized state-space models require derivation under the condition that the models and parameters of all components in the grid-connected system are known. In practice, due to reasons such as manufacturer intellectual property protection, the control models and parameters of new energy units are usually unknown. Therefore, model analysis is difficult to apply to engineering practice and is generally only applicable to theoretical analysis. Numerical results of the impedance model of new energy units can be obtained through frequency domain disturbance experiments, thus impedance analysis has practical engineering value. However, due to the small capacity of a single unit, new energy power plants typically have dozens or even hundreds of new energy units, resulting in high system model order and a large amount of computation for stability analysis. In particular, during the power plant planning stage, different network topologies and the number of units need to be considered, leading to a large amount of computation for stability verification. Summary of the Invention

[0005] This application provides a method, device, electronic equipment, and storage medium for determining the oscillation of new energy power plants, in order to solve the problem of unknown new energy unit models and parameters in practice, effectively reducing the amount of calculation in the oscillation stability analysis of new energy power plants and improving work efficiency.

[0006] The first aspect of this application provides an oscillation determination method for a renewable energy power station, comprising the following steps: obtaining impedance models of target renewable energy units in a grid-connected renewable energy power station under multiple preset operating conditions; based on the impedance models, outputting the impedance ratio matrix feature values ​​of the target renewable energy units under each preset operating condition, and generating a Nyquist curve from the impedance ratio matrix feature values ​​of the target renewable energy units under each preset operating condition; and determining whether the grid-connected renewable energy power station has an oscillation risk based on the Nyquist curve, and when the grid-connected renewable energy power station has an oscillation risk, obtaining the oscillation result of the grid-connected renewable energy power station based on a preset stability criterion and the network reactance matrix of the grid-connected renewable energy power station.

[0007] Optionally, in some embodiments, determining whether the grid-connected renewable energy power station has an oscillation risk based on the Nyquist curve includes: determining whether the net counterclockwise closed portion of the Nyquist curve intersects with the negative real axis of the preset coordinate axis under multiple preset operating conditions; if the intersection exists under multiple preset operating conditions, it is determined that the grid-connected renewable energy power station has an oscillation risk; otherwise, it is determined that the grid-connected renewable energy power station does not have an oscillation risk.

[0008] Optionally, in some embodiments, the network reactance matrix of the grid-connected renewable energy power station is:

[0009]

[0010] Where, if i≠j, x ij For the common reactance of the line connecting the i-th and j-th generating units to the grid connection point PCC, if i = j, x ii Let i,j = 1,2,…,M be the line reactance connecting the i-th generating unit to the grid connection point PCC.

[0011] Optionally, in some embodiments, the preset stability criterion is:

[0012]

[0013] Where, λ M is the maximum eigenvalue of the reactance matrix of the grid-connected new energy power station network, and (-a,0) is the intersection point of the net counterclockwise closed portion of the Nyquist curve and the negative real axis of the preset coordinate axis.

[0014] A second aspect of this application provides an oscillation determination device for a renewable energy power station, comprising: an acquisition module for acquiring impedance models of target renewable energy units in a grid-connected renewable energy power station under multiple preset operating conditions; a generation module for outputting impedance ratio matrix feature values ​​of the target renewable energy units under each preset operating condition based on the impedance models, and generating a Nyquist curve from the impedance ratio matrix feature values ​​of the target renewable energy units under each preset operating condition; and a determination module for determining whether the grid-connected renewable energy power station has an oscillation risk based on the Nyquist curve, and obtaining the oscillation result of the grid-connected renewable energy power station based on a preset stability criterion and the network reactance matrix of the grid-connected renewable energy power station when the grid-connected renewable energy power station has an oscillation risk.

[0015] Optionally, in some embodiments, the determination module is used to: determine whether the net counterclockwise closed portion of the Nyquist curve intersects with the negative real axis of the preset coordinate axis under the plurality of preset operating conditions; if the intersection point exists under the plurality of preset operating conditions, then the grid-connected new energy power station is determined to have an oscillation risk; otherwise, the grid-connected new energy power station is determined not to have an oscillation risk.

[0016] Optionally, in some embodiments, the network reactance matrix of the grid-connected renewable energy power station is:

[0017]

[0018] Where, if i≠j, x ij For the common reactance of the line connecting the i-th and j-th generating units to the grid connection point PCC, if i = j, x ii Let i,j = 1,2,…,M be the line reactance connecting the i-th generating unit to the grid connection point PCC.

[0019] Optionally, in some embodiments, the preset stability criterion is:

[0020]

[0021] Where, λ M denoted as the maximum eigenvalue of the reactance matrix of the grid-connected new energy power station network, and 'a' is the intersection point of the net counterclockwise closed portion of the Nyquist curve and the negative real axis of the preset coordinate axis.

[0022] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor executes the program to implement the oscillation determination method for new energy power stations as described in the above embodiments.

[0023] A fourth aspect of this application provides a computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement the oscillation determination method for new energy power stations as described in the above embodiments.

[0024] Therefore, the oscillation determination method for new energy power plants in this application only requires plotting the Nyquist curves of the impedance ratio matrix eigenvalues ​​of a single-unit grid-connected system under different operating conditions. Based on this, the oscillation stability of grid-connected new energy power plants under different operating conditions, network topologies, and numbers of units can be determined. There is no need to establish a power plant model or perform stability calculations, which effectively reduces the computational load in the oscillation stability analysis of large-scale new energy power plants. At the same time, it can be used for oscillation stability verification of new energy power plants in the planning stage. The impedance model can be obtained through measurement, which solves the problem of unknown new energy unit models and parameters in practice. Considering different numbers of units and network topologies, only the eigenvalues ​​of the network reactance matrix need to be calculated, without having to repeatedly establish a model of the grid-connected new energy power plant, which effectively reduces the computational load of stability verification in the planning stage and improves work efficiency.

[0025] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0026] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0027] Figure 1 This is a flowchart of the oscillation determination method for new energy power stations provided in the embodiments of this application;

[0028] Figure 2 This is a block diagram illustrating an oscillation determination method for a new energy power station according to an embodiment of this application;

[0029] Figure 3 This is a schematic diagram of a grid-connected renewable energy power station according to an embodiment of this application;

[0030] Figure 4 This is a schematic diagram of an equivalent stand-alone grid-connected system according to an embodiment of this application;

[0031] Figure 5 This is a flowchart of a stability verification process according to an embodiment of this application;

[0032] Figure 6 This is a block diagram of an oscillation determination device for a new energy power station provided according to an embodiment of this application;

[0033] Figure 7 This is a schematic diagram of an electronic device provided according to an embodiment of this application. Detailed Implementation

[0034] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0035] The following description, with reference to the accompanying drawings, outlines a method, apparatus, electronic device, and storage medium for determining the oscillation of a renewable energy power station according to embodiments of this application. Addressing the challenge mentioned in the background section regarding the unknown models and parameters of renewable energy generating units in practice, this application provides a method for determining the oscillation of a renewable energy power station. This method obtains the impedance models of target renewable energy generating units in a grid-connected renewable energy power station under multiple preset operating conditions. Based on these impedance models, it outputs the impedance ratio matrix eigenvalues ​​of the target renewable energy generating units under each preset operating condition. A Nyquist curve is generated from the impedance ratio matrix eigenvalues ​​of the target renewable energy generating units under each preset operating condition. The Nyquist curve is used to determine whether the grid-connected renewable energy power station has an oscillation risk. If an oscillation risk exists, the oscillation result of the grid-connected renewable energy power station is obtained based on a preset stability criterion and the network reactance matrix of the grid-connected renewable energy power station. This solves the problem of unknown models and parameters of renewable energy generating units in practice, effectively reduces the computational load in the oscillation stability analysis of renewable energy power stations, and improves work efficiency.

[0036] Specifically, Figure 1 This is a flowchart illustrating a method for determining the oscillation of a new energy power station, as provided in an embodiment of this application.

[0037] like Figure 1 As shown, the oscillation determination method for this new energy power station includes the following steps:

[0038] In step S101, the impedance models of the target new energy units in the grid-connected new energy power stations under multiple preset operating conditions are obtained.

[0039] Specifically, considering that the control model and parameters of new energy units are usually unknown and their dynamic characteristics are affected by changes in operating conditions, the new energy units can be set to operate under different operating conditions, and the numerical results of the unit impedance model under each operating condition can be obtained through disturbance experiments.

[0040] The new energy generator unit is controlled to operate under different operating conditions by a prime mover or power source, and a disturbance current with frequency f is added to the unit port. The voltage and output current of the unit port during the disturbance are measured. The components with angular frequency ω = 2πf in the measured voltage and current are extracted by Fourier transform, so that the impedance model numerical result of the unit at this time can be obtained. The calculation formula is shown in Equation (1). By changing the frequency of the injected disturbance current, the impedance model of the new energy generator unit in the frequency band of interest can be measured.

[0041]

[0042] In the formula, the transformation from the abc three-phase coordinate system to the dq coordinate system can be obtained based on the Park transformation principle according to the setting of the reference coordinate system.

[0043] In step S102, based on the impedance model, the impedance ratio matrix eigenvalues ​​of the target new energy unit under each preset operating condition are output, and the Nyquist curve is generated from the impedance ratio matrix eigenvalues ​​of the target new energy unit under each preset operating condition.

[0044] Specifically, the impedance ratio matrix -Z under the operating condition of interest is plotted. g -1 Nyquist curve of eigenvalues ​​of E(s)E(s).

[0045] In step S103, the presence of oscillation risk in the grid-connected renewable energy power station is determined based on the Nyquist curve. If the grid-connected renewable energy power station has an oscillation risk, the oscillation result of the grid-connected renewable energy power station is obtained based on the preset stability criterion and the network reactance matrix of the grid-connected renewable energy power station.

[0046] Optionally, in some embodiments, the network reactance matrix of the grid-connected renewable energy power station is:

[0047]

[0048] Where, if i≠j, x ij For the common reactance of the line connecting the i-th and j-th generating units to the grid connection point PCC, if i = j, x ii Let i,j = 1,2,…,M be the line reactance connecting the i-th generating unit to the grid connection point PCC.

[0049] Optionally, in some embodiments, the preset stability criterion is:

[0050]

[0051] Where, λ M denoted as the maximum eigenvalue of the reactance matrix of the grid-connected renewable energy power station network, and 'a' is the intersection point of the net counterclockwise closed portion of the Nyquist curve and the negative real axis of the preset coordinate axis.

[0052] Optionally, in some embodiments, determining whether there is an oscillation risk in the grid-connected renewable energy power station based on the Nyquist curve includes: under multiple preset operating conditions, determining whether the net counterclockwise closed portion of the Nyquist curve intersects with the negative real axis of the preset coordinate axis; if there is an intersection under multiple preset operating conditions, it is determined that there is an oscillation risk in the grid-connected renewable energy power station; otherwise, it is determined that there is no oscillation risk in the grid-connected renewable energy power station.

[0053] Specifically, the presence of oscillation risk in the grid-connected system is determined based on whether the net counterclockwise closed portion intersects with the negative real axis. If no oscillation risk exists, the analysis ends. If a risk exists, subsequent analysis is conducted.

[0054] Specifically, if the impedance ratio matrix -Z g -1 The Nyquist curve of the eigenvalues ​​of E(s) encircles the points on the negative real axis in a net counterclockwise direction, and the leftmost intersection point is (-a, 0) under all considered operating conditions. The network reactance matrix X is formed based on the network topology of the grid-connected new energy power station. R And calculate its eigenvalues ​​to obtain λ. M And based on the stability criterion shown in Equation (3), it is determined whether the grid-connected new energy power station will oscillate and become unstable.

[0055] It should be noted that if the number of units or network topology within the site changes, the analysis process in S103 should be repeated.

[0056] To enable those skilled in the art to further understand the oscillation determination method for new energy power stations according to the embodiments of this application, the following detailed description is provided in conjunction with specific embodiments.

[0057] In this embodiment, a stability criterion for determining the oscillation stability of multi-unit grid-connected renewable energy power plants is established using an impedance ratio matrix based on a single unit and unit-length reactance. This achieves the goal of determining the oscillation stability of a renewable energy power plant simply by measuring and analyzing the characteristics of a single unit. The invention's content and method block diagram are as follows: Figure 2 As shown, the specific explanation and export process are as follows:

[0058] Figure 3 The figure shows a grid-connected renewable energy power station with M generators. The small-signal impedance model of the j-th renewable energy unit can be written as follows:

[0059] ΔV j =Z j (s)ΔI j (4)

[0060] In the formula, I j =[I jx I jy ] T V j =[V jx V jy ] T ;I jx +jI jy and V jx +jV jy Z represents the output current and terminal voltage of the k-th renewable energy unit in the common xy coordinate system of the AC system, respectively; Δ represents the infinitesimal increment of the variable or variable vector; Zj (s) is the transfer function (impedance) matrix of the j-th unit; j = 1, 2, ..., M.

[0061] Using the PCC bus as the reference node, Figure 3 The node voltage equation for the grid-connected renewable energy power station shown is as follows:

[0062] ΔV R =Z R (s)ΔI R +ΔV PCCM (5)

[0063] In the formula, V R =[V1 T V2 T … V M T ] T I R =[I1 T I2 T … I M T ] T V PCCM =[V PCC T V PCC T … V PCC T ] T ∈R 2M×1 V PCC =[V PCCx V PCCy ] T V PCCx +jV PCCy Z represents the voltage at the new energy grid connection point (bus PCC) in the common xy coordinate system; R (s) represents the node impedance matrix of the grid-connected renewable energy power station.

[0064] From equation (4),

[0065] ΔV R =diag[Z j (s)]ΔI R (6)

[0066] In the formula, diag[Z j [s] indicates that the diagonal element is Z. j The block diagonal matrix of (s), j = 1, 2, ..., M.

[0067] The current on a new energy transmission line can be expressed as,

[0068]

[0069] In the formula, I pcc =[I pccx I pccy ] T I pccx +jI pccy This refers to the current injected into the external AC power grid by a new energy power station in the common xy coordinate system.

[0070] Combining equations (5), (6), and (7), we can obtain...

[0071] ΔV PCC =Z station (s)ΔI pcc (8)

[0072] In the formula, Z station (s) is the transfer function (impedance) matrix of the grid-connected renewable energy power station; and [m ij (s)]| i，j＝1，2，…，M ={diag[Z j (s)]-Z R (s)}-1 is a 2M×2M block matrix, and the elements in each block are m. ij (s)(2×2 matrix).

[0073] Considering the case where the dynamics of the generating units within a new energy power station are approximately the same, that is, we have,

[0074] Z1(s)≈Z2(s)…≈Z k (s)…≈Z M (s)=Z g (s); (9)

[0075] The following is a further explanation of the above assumptions:

[0076] 1) In practice, a new energy power station generally uses generators from the same manufacturer and of the same model, so the generators can be considered to have certain similarities in dynamic characteristics.

[0077] 2) For a new energy power station, if all units have the same dynamic characteristics as the unit with the "worst" stability, then the "ideal grid-connected new energy power station" will have the worst stability. Therefore, the boundary of the system oscillation stability can be analyzed based on the assumption shown in equation (9).

[0078] Ignoring line resistance, the impedance matrix of grid-connected new energy power station nodes in equation (5) can be expressed as follows:

[0079]

[0080] In the formula, XR For grid-connected renewable energy power plants, a network reactor matrix is ​​required. Represents the Kronecker product;

[0081] The network reactance matrix X in equation (10) R The representation of is as follows:

[0082]

[0083] In the formula, if i ≠ j, x ij For the common reactance of the line connecting the i-th and j-th generating units to the grid connection point PCC, if i = j, x ii Let i be the line reactance connecting the i-th generating unit to the grid connection point PCC; i, j = 1, 2, ..., M.

[0084] Based on the properties of the node impedance matrix, the network reactance matrix shown in equation (11) is a real symmetric matrix. Let λ i and u i =[u 1i u 2i … u Mi ] T Let represent its eigenvalues ​​and corresponding eigenvectors (i = 1, 2, ..., M), then we have:

[0085] U -1 X R U = diag[λ] i (12)

[0086] In the formula, U=[u1 u2…u M ] is composed of column vector u i The 2M×2M matrix formed, diag[λ] i ] indicates that the diagonal element is λ i A diagonal matrix (i = 1, 2, ..., M).

[0087] Based on equation (12), the following variable transformation is introduced:

[0088] ΔV R =U2ΔV Y ΔI R =U2ΔI Y (13)

[0089] In the formula, E2 is a 2×2 identity matrix.

[0090] Substituting equations (9) and (13) into equation (6) yields the following result:

[0091] ΔV Y =U2-1 diag[Z g (s)]U2ΔI Y

[0092] =diag[Z g (s)]ΔI Y (14)

[0093] Substituting equations (10) and (13) into equation (5) yields the following:

[0094] ΔV Y =daig[λ i E(s)]ΔI Y +u s ΔV PCC (15)

[0095] In the formula, u s =[u1 u2 … u M ] T ; For the feature vector u i The sum of all elements in the set, i = 1, 2, ..., M.

[0096] Based on equations (14) and (15), under the assumptions shown in equation (9), the impedance model of the M-machine grid-connected new energy power station shown in equation (8) can be decoupled into M mutually independent equivalent subsystems, as follows:

[0097]

[0098] In the formula, i = 1, 2, ..., M, the equivalent subsystem can be regarded as a system with impedance model Z g (s) new energy generating units, with reactance λ i The network is composed of interconnected lines, and the specific structure is as follows: Figure 4 As shown.

[0099] The equivalent subsystem model shown in equation (16) can be further written in the following form (i = 1, 2, ..., M),

[0100] ΔV PCC =u i -1 [Z g (s)-λ i E(s)]ΔI Yi (17)

[0101] The oscillation stability of the original grid-connected renewable energy power station can be analyzed based on the equivalent subsystem model shown in Equation (17). According to the generalized Nyquist criterion, for the i-th equivalent subsystem shown in Equation (17), if the impedance ratio matrix -λ i Z g-1 If the net Nyquist curve of the eigenvalues ​​E(s) and the number of counterclockwise loops around (-1, 0) of the Nyquist curve is 0, then the equivalent subsystem is stable. Based on this, if we let the impedance ratio matrix -Z... g -1 If the eigenvalues ​​of E(s) are R1(s) and R2(s), then the impedance ratio matrix -λ i Z g -1 The eigenvalues ​​of E(s) can be expressed as R i1 (s)=λ i R1(s) and R i2 (s)=λ i R2(s). Due to matrix X R Let λ be a positive real symmetric matrix. i All are positive real numbers, i = 1, 2, ..., M. If we follow the rule 0 < λ1 ≤ λ2 ≤ ... ≤ λ... M If arranged in order, then:

[0102] 1) If the Nyquist curves of R1(s) and R2(s) do not "netly" encircle points on the negative real axis counterclockwise, then regardless of λ i How does R change? i1 (s) and R i2 The Nyquist curve of (s) will not "net" encircle the points on the negative real axis counterclockwise, that is, it will not "net" encircle (-1, 0) counterclockwise, thus the equivalent subsystem is always stable, that is, the original grid-connected new energy power station is always stable.

[0103] 2) If the net counterclockwise closed portion of the Nyquist curves R1(s) and R2(s) (from left to right along the negative real axis, considering the first round of net counterclockwise closed curve after cancellation with the clockwise closed curve) intersects the negative real axis at a point with coordinates (-a, 0) (a > 0), then R i1 (s) and R i2 (s) The intersection point of the net counterclockwise closed portion of the Nyquist curve with the negative real axis is (-λ). i a, 0), if -λ M If a < -1, then the Mth equivalent subsystem becomes unstable, i.e., the original grid-connected new energy power station becomes unstable.

[0104] In summary, if the Nyquist curve of the eigenvalues ​​of a single renewable energy unit and the reactance-impedance ratio matrix encircles a point on the negative real axis in a net counterclockwise direction, then the grid-connected renewable energy power station faces oscillation risk; otherwise, there is no oscillation risk. For cases where oscillation risk exists, the stability criterion is as follows:

[0105]

[0106] In the formula, λ MThe maximum eigenvalue of the network reactance matrix of grid-connected renewable energy power plants.

[0107] According to the oscillation determination method for new energy power stations proposed in the embodiments of this application, the following can be adopted: Figure 5 Step-by-step calculation.

[0108] Step 1: Measure the impedance model of the selected new energy unit under various operating conditions.

[0109] By setting the new energy generating unit to operate under various operating conditions of interest, and through frequency domain perturbation experiments, the numerical results of the unit's frequency impedance model were obtained.

[0110] Step 2: Draw the impedance ratio matrix of a single unit to determine if there is a risk of oscillation.

[0111] 1) Draw the impedance ratio matrix -Z under each operating condition. g -1 Nyquist curve of eigenvalues ​​of E(s);

[0112] 2) If the net counterclockwise closed portion of the Nyquist curve intersects the negative real axis, and the coordinates of the leftmost intersection point under each operating condition are (-a, 0) (a>0), then the grid-connected renewable energy power station is at risk of oscillation and instability; otherwise, there is no risk.

[0113] Step 3: Analyze the oscillation stability of grid-connected renewable energy power plants under each planning scheme.

[0114] 1) For each planning scheme, form its network reactance matrix and calculate the matrix eigenvalues ​​to obtain the maximum eigenvalue λ of the network reactance matrix for each scheme. M ;

[0115] 2) Based on the stability criterion shown in equation (3), determine the oscillation stability of the grid-connected new energy power station under each scheme.

[0116] Therefore, this application embodiment considers that in practice, new energy power stations typically use generators from the same manufacturer and of the same model, with similar dynamic characteristics. During the planning phase, it can be assumed that the dynamics of each generator are identical. Based on this, and using the equivalent decoupling method for multi-agent systems in consensus control theory, an N-generator new energy power station can be decoupled into N independent equivalent subsystems, each consisting of a single new energy generator connected to the grid. Based on the decoupled single-generator grid-connected subsystems, a stability criterion is proposed to determine the oscillation risk of grid-connected new energy power stations under different network topologies and numbers of new energy generators, based on the single-generator impedance ratio matrix. Based on the proposed criterion, only the impedance model of one generator needs to be measured to determine the oscillation stability of the grid-connected new energy power station, eliminating the need to establish a station model and perform stability calculations. This effectively reduces the computational load of stability verification during the station planning phase and improves work efficiency.

[0117] The oscillation determination method for renewable energy power plants proposed in this application involves obtaining the impedance models of target renewable energy units in grid-connected renewable energy power plants under multiple preset operating conditions. Based on the impedance models, the impedance ratio matrix eigenvalues ​​of the target renewable energy units under each preset operating condition are output. A Nyquist curve is generated from the impedance ratio matrix eigenvalues ​​of the target renewable energy units under each preset operating condition. The Nyquist curve is used to determine whether there is an oscillation risk in the grid-connected renewable energy power plant. When an oscillation risk exists, the oscillation result of the grid-connected renewable energy power plant is obtained based on a preset stability criterion and the network reactance matrix of the grid-connected renewable energy power plant. This solves the problem of unknown renewable energy unit models and parameters in practice, effectively reduces the computational load in the oscillation stability analysis of renewable energy power plants, and improves work efficiency.

[0118] Next, referring to the accompanying drawings, an oscillation determination device for a new energy power station proposed according to an embodiment of this application is described.

[0119] Figure 6 This is a block diagram of the oscillation determination device for a new energy power station according to an embodiment of this application.

[0120] like Figure 6 As shown, the oscillation determination device 10 of the new energy power station includes: an acquisition module 100, a generation module 200 and a determination module 300.

[0121] The system includes: an acquisition module 100 for acquiring impedance models of target renewable energy units in grid-connected renewable energy power plants under multiple preset operating conditions; a generation module 200 for outputting impedance ratio matrix eigenvalues ​​of target renewable energy units under each preset operating condition based on the impedance models, and generating Nyquist curves from the impedance ratio matrix eigenvalues ​​of target renewable energy units under each preset operating condition; and a judgment module 300 for judging whether there is an oscillation risk in the grid-connected renewable energy power plant based on the Nyquist curve, and obtaining the oscillation result of the grid-connected renewable energy power plant based on preset stability criteria and the network reactance matrix of the grid-connected renewable energy power plant when there is an oscillation risk.

[0122] Optionally, in some embodiments, the determination module 300 is used to: determine whether the net counterclockwise closed portion of the Nyquist curve intersects with the negative real axis of the preset coordinate axis under multiple preset operating conditions; if there is an intersection under multiple preset operating conditions, it is determined that the grid-connected new energy power station has an oscillation risk; otherwise, it is determined that the grid-connected new energy power station does not have an oscillation risk.

[0123] Optionally, in some embodiments, the network reactance matrix of the grid-connected renewable energy power station is:

[0124]

[0125] Where, if i≠j, x ijFor the common reactance of the line connecting the i-th and j-th generating units to the grid connection point PCC, if i = j, x ii Let i,j = 1,2,…,M be the line reactance connecting the i-th generating unit to the grid connection point PCC.

[0126] Optionally, in some embodiments, the preset stability criterion is:

[0127]

[0128] Where, λ M is the maximum eigenvalue of the reactance matrix of the grid-connected new energy power station network, and (-a,0) is the intersection point of the net counterclockwise closed portion of the Nyquist curve and the negative real axis of the preset coordinate axis.

[0129] It should be noted that the explanation of the above-mentioned embodiment of the oscillation determination method for new energy power stations also applies to the oscillation determination device for new energy power stations in this embodiment, and will not be repeated here.

[0130] The oscillation determination device for renewable energy power plants proposed in this application obtains the impedance models of target renewable energy units in grid-connected renewable energy power plants under multiple preset operating conditions. Based on the impedance models, it outputs the impedance ratio matrix eigenvalues ​​of the target renewable energy units under each preset operating condition, generates a Nyquist curve from the impedance ratio matrix eigenvalues ​​of the target renewable energy units under each preset operating condition, and determines whether there is an oscillation risk in the grid-connected renewable energy power plant based on the Nyquist curve. When there is an oscillation risk, the oscillation result of the grid-connected renewable energy power plant is obtained based on a preset stability criterion and the network reactance matrix of the grid-connected renewable energy power plant. This solves the problem of unknown renewable energy unit models and parameters in practice, effectively reduces the computational load in the oscillation stability analysis of renewable energy power plants, and improves work efficiency.

[0131] Figure 7 A schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device may include:

[0132] The memory 701, the processor 702, and the computer program stored on the memory 701 and executable on the processor 702.

[0133] When the processor 702 executes the program, it implements the oscillation determination method for new energy power stations provided in the above embodiments.

[0134] Furthermore, electronic devices also include:

[0135] Communication interface 703 is used for communication between memory 701 and processor 702.

[0136] The memory 701 is used to store computer programs that can run on the processor 702.

[0137] The memory 701 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0138] If the memory 701, processor 702, and communication interface 703 are implemented independently, then the communication interface 703, memory 701, and processor 702 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of representation, Figure 7 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0139] Optionally, in a specific implementation, if the memory 701, processor 702, and communication interface 703 are integrated on a single chip, then the memory 701, processor 702, and communication interface 703 can communicate with each other through an internal interface.

[0140] The processor 702 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0141] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the above-described method for determining the oscillation of a new energy power station.

[0142] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0143] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0144] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0145] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0146] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0147] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0148] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0149] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for determining oscillations in a new energy power station, characterized in that, Includes the following steps: Obtain the impedance model of the target renewable energy unit in the grid-connected renewable energy power station under multiple preset operating conditions; Based on the impedance model, the impedance ratio matrix feature value of the target new energy unit under each preset operating condition is output, and the Nyquist curve is generated from the impedance ratio matrix feature value of the target new energy unit under each preset operating condition; as well as The Nyquist curve is used to determine whether the grid-connected renewable energy power station has an oscillation risk. If the grid-connected renewable energy power station has an oscillation risk, the oscillation result of the grid-connected renewable energy power station is obtained based on a preset stability criterion and the network reactance matrix of the grid-connected renewable energy power station. The step of obtaining the impedance model of the target renewable energy unit in the grid-connected renewable energy power station under multiple preset operating conditions includes: The new energy generator unit is controlled to operate under different conditions by a prime mover or power source, and a frequency is applied to the port of the new energy generator unit. The disturbance current is measured, and the port voltage and output current of the new energy unit are measured during the disturbance period; the angular frequency of the measured port voltage and output current is extracted by Fourier transform. The components are used to obtain the impedance model; The preset stability criterion is: ； in, The maximum eigenvalue of the reactance matrix of the grid-connected renewable energy power station network is [value missing]. The point where the net counterclockwise closed portion of the Nyquist curve intersects the negative real axis of the preset coordinate axis is called.

2. The method according to claim 1, characterized in that, The determination of whether the grid-connected renewable energy power station has oscillation risk based on the Nyquist curve includes: Under the multiple preset operating conditions, determine whether the net counterclockwise closed portion of the Nyquist curve intersects with the negative real axis of the preset coordinate axis. If the intersection point exists under any preset operating condition, it is determined that the grid-connected new energy power station has an oscillation risk; otherwise, it is determined that the grid-connected new energy power station does not have an oscillation risk.

3. The method according to claim 1, characterized in that, The network reactance matrix of the grid-connected renewable energy power station is as follows: ； Among them, if , To connect the first Taiwan and the The common part reactance of the line from the generator unit to the grid connection point PCC, if , To connect the first Line reactance from the generator unit to the grid connection point PCC, .

4. An oscillation determination device for a new energy power station, characterized in that, include: The acquisition module is used to acquire the impedance models of target renewable energy units in grid-connected renewable energy power stations under multiple preset operating conditions; The generation module is used to output the impedance ratio matrix feature value of the target new energy unit under each preset operating condition based on the impedance model, and generate the Nyquist curve from the impedance ratio matrix feature value of the target new energy unit under each preset operating condition; as well as The determination module is used to determine whether the grid-connected renewable energy power station has an oscillation risk based on the Nyquist curve, and when the grid-connected renewable energy power station has an oscillation risk, to obtain the oscillation result of the grid-connected renewable energy power station based on a preset stability criterion and the network reactance matrix of the grid-connected renewable energy power station. The step of obtaining the impedance model of the target renewable energy unit in the grid-connected renewable energy power station under multiple preset operating conditions includes: The new energy generator unit is controlled to operate under different conditions by a prime mover or power source, and a frequency is applied to the port of the new energy generator unit. The disturbance current is measured, and the port voltage and output current of the new energy unit are measured during the disturbance period; the angular frequency of the measured port voltage and output current is extracted by Fourier transform. The components are used to obtain the impedance model; The preset stability criterion is: ； in, The maximum eigenvalue of the reactance matrix of the grid-connected renewable energy power station network is [value missing]. The point where the net counterclockwise closed portion of the Nyquist curve intersects the negative real axis of the preset coordinate axis is called.

5. The apparatus according to claim 4, characterized in that, The determination module is used for: Under the multiple preset operating conditions, determine whether the net counterclockwise closed portion of the Nyquist curve intersects with the negative real axis of the preset coordinate axis. If the intersection point exists under all of the preset operating conditions, it is determined that the grid-connected new energy power station has an oscillation risk; otherwise, it is determined that the grid-connected new energy power station does not have an oscillation risk.

6. The apparatus according to claim 4, characterized in that, The network reactance matrix of the grid-connected renewable energy power station is as follows: ； Among them, if , To connect the first Taiwan and the The common part reactance of the line from the generator unit to the grid connection point PCC, if , To connect the first Line reactance from the generator unit to the grid connection point PCC, .

7. An electronic device, characterized in that, include: The device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the oscillation determination method for a new energy power station as described in any one of claims 1-3.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the oscillation determination method for new energy power stations as described in any one of claims 1-3.

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