Method, device and equipment for analyzing broadband oscillation characteristics of hybrid power system with grid-forming and grid-following types and storage medium

Abstract

The application provides a method, device and equipment for analyzing broadband oscillation characteristics of a follow-grid-construction grid hybrid power system and a storage medium. The application relates to the technical field of power grid control. The method comprises the following steps: when the follow-grid-construction grid hybrid power system is at a steady-state equilibrium point, a disturbance is applied to a state equation of the system, a branch mode energy function at an outlet of a follow-grid type wind turbine is determined, and a branch mode energy function at an outlet of a construction grid type wind turbine is determined according to an active power-frequency control equation of a grid-side converter; the branch mode energy function at the outlet of the follow-grid type wind turbine and the branch mode energy function at the outlet of the construction grid type wind turbine are superposed to obtain a mode energy curve, parameter identification is performed, energy amplitudes and frequencies of different modes are obtained, and the participation degrees of the different modes in oscillation are further determined. The application identifies mode energy components in different frequency bands by constructing mode energy functions at outlets of follow-grid type wind turbines and construction grid type wind turbines, and can accurately determine a dominant oscillation mode.

Description

Technical Field

[0001] This application relates to the field of power grid control technology, and in particular to a method, apparatus, equipment and storage medium for analyzing the broadband oscillation characteristics of a grid-connected hybrid power system. Background Technology

[0002] In recent years, with the integration of a high proportion of new energy sources and power electronic equipment into the power grid, the inertia of the existing power grid has begun to decrease significantly, and new stability issues have emerged. In particular, the integration of new energy sources such as wind and solar power has led to varying degrees of deterioration in the grid strength and stability of the new power systems. Therefore, ensuring the stability of the new power systems is a pressing issue. The key to achieving stability lies in identifying the dominant oscillation mode. Once the dominant oscillation mode is determined, targeted adjustments can be made to ensure system stability. Summary of the Invention

[0003] This application provides a method, apparatus, equipment, and storage medium for analyzing broadband oscillation characteristics of a grid-connected and grid-connected hybrid power system. By constructing mode energy functions at the outlets of grid-connected and grid-connected wind turbines, the mode energy components at different frequency bands are identified, thereby determining the dominant oscillation mode.

[0004] Firstly, this application provides a method for analyzing the broadband oscillation characteristics of a grid-connected hybrid power system, including:

[0005] When the grid-connected and grid-connected hybrid power system is at a steady-state equilibrium point, the state equation of the system is disturbed to determine the branch mode energy function of the grid-connected wind turbine outlet, and the branch mode energy function of the grid-connected wind turbine outlet is determined according to the active power-frequency control equation of the grid-side converter.

[0006] The branch mode energy function at the outlet of the grid-type wind turbine is superimposed with the branch mode energy function at the outlet of the grid-type wind turbine to obtain the mode energy curve. The parameters of the mode energy curve are identified to obtain the energy amplitude and frequency of different modes. Based on the energy amplitude of different modes, the participation degree of different modes in the oscillation is determined.

[0007] Furthermore, when the grid-connected hybrid power system is at its steady-state equilibrium point, a disturbance is applied to the system's state equations to determine the branch mode energy function at the outlet of the grid-connected wind turbine, including:

[0008] When a grid-connected hybrid power system is at its steady-state equilibrium point, applying a disturbance to the system's state equations yields:

[0009]

[0010] In the formula, The derivative of a state variable; Δx Represents state variables; Δu The input variables are represented by A, B, C, and D, which represent the state matrix, input matrix, output matrix, and feedforward matrix, respectively.

[0011] The general solution of the system's state equations is as follows:

[0012]

[0013] In the formula, Δx(t) represents the general solution of the state equation; ψ i , Let x and λ represent the left and right eigenvectors, respectively; x0 represents the initial value of the system state variable; λ i The system characteristic value is represented by t; time is represented by t.

[0014] After applying a disturbance to the system's state equations, the expression for the branch energy is determined as follows:

[0015] V=∫(P ijs +ΔP ij )d(θ is +Δθ i )+∫(Q ijs +ΔQ ij )d(lnU is +ΔlnU i (3)

[0016] In the formula, Δ represents a small disturbance; s represents the steady-state value of the relevant electrical quantity; V represents the energy transmitted by the branch; P ijs ΔP represents the steady-state value of active power transmitted at nodes i and j; ij θ represents the increment of active power transmitted at nodes i and j; is θ represents the steady-state phase angle at node i; i U represents the phase angle at node i; i The voltage at node i is represented by d; d represents the integral sign.

[0017] Based on the expression for branch energy, and taking transient quantities as the research object, the expression for branch mode energy is obtained as follows:

[0018] ΔV=∫ΔP ij d(Δθ i (4)

[0019] In the formula, ΔV represents the branch mode energy;

[0020] The electromagnetic power delivered by wind turbines using grid-following and grid-connected control is determined by the following formula:

[0021] P e=U1U2(sinδ 12 ) / X 12 (5)

[0022] In the formula, U1 represents the voltage amplitude at the new energy collection point, and U2 represents the voltage amplitude at the PCC bus; δ 12 This represents the phase angle difference between the new energy collection point and the PCC bus; X 12 P represents the line reactance between the collection point and the PCC bus; e This indicates that the electromagnetic power delivered by new energy sources in a hybrid power system is composed of both grid-connected and grid-connected wind turbines.

[0023] P e =P e-GFL +P e-GFM (6)

[0024] In the formula, P e-GFL Indicates the active power delivered by the grid-type wind turbine; P e-GFM This indicates the active power delivered by the grid-type wind turbine;

[0025] Taking wind turbine generators as the research object, we linearize their output active power to obtain:

[0026]

[0027] In the formula, k δ C represents the synchronization coefficient of the fan; dc ΔP represents the DC capacitance between the back-to-back converters; ΔP1 represents the active power output of the wind turbine after linearization; k0, k1, k2, k3, and k4 are all gain coefficients; ΔP u represents the active power output of the wind turbine; s represents the Laplace operator;

[0028] The branch mode energy function at the outlet of the grid-type fan is determined as follows:

[0029]

[0030] In the formula, ΔP es1 ΔP ed1 These represent the incremental forms of the synchronous and damped components of the active power, respectively; Δθ es1 , Δθ es1 These represent the incremental forms of the synchronous and damping components of the phase angle, respectively; ΔV p-GFL This represents the branch mode energy function at the outlet of the grid-type wind turbine.

[0031] Furthermore, the active power-frequency control equation of the grid-side converter is expressed as:

[0032]

[0033] In the formula, J represents the moment of inertia; P ref Indicates the active power reference value; P represents active power; ω ref ω represents the rotor angular velocity reference value; D represents the damping coefficient; θ represents the shaft torsion angle.

[0034] Furthermore, based on the active power-frequency control equation of the grid-side converter, the branch mode energy function at the outlet of the grid-connected wind turbine is determined, including:

[0035] Based on the active power-frequency control equation of the grid-side converter, the active power delivered by the grid-connected wind turbine is obtained as shown in the following formula:

[0036] P e-GFM =P ref -(Jω+D)(ω-ω ref (10)

[0037] In the formula, P e-GFM This indicates the active power delivered by the grid-type wind turbine;

[0038] Linearizing equation (10), we obtain the increase in active power ΔP delivered by the grid-type wind turbine. e-GFM As shown in the following formula:

[0039] ΔP e-GFM =-(JΔω+D)Δω (11)

[0040] The mode energy function of the outlet branch of the grid-type wind turbine is shown in the following equation:

[0041] ΔV p-GFM =∫ΔP e-GFM dΔθ (12)

[0042] In the formula, ΔV e-GFM The mode energy function representing the outlet branch of a grid-type wind turbine;

[0043] In equation (9) Linearization and substitution into equation (12) yields the branch mode energy function at the outlet of the grid-type wind turbine:

[0044]

[0045] Furthermore, the Prony algorithm is used to identify the parameters of the mode energy curve.

[0046] Furthermore, the methods for determining the participation of different modes in the oscillation based on the energy amplitude of different modes include: determining the participation of different modes in the oscillation based on the magnitude of the energy amplitude; the larger the energy amplitude, the higher the participation of the corresponding mode in the oscillation, and the mode with the largest energy amplitude is determined as the dominant oscillation mode.

[0047] Secondly, this application provides a broadband oscillation characteristic analysis device for a grid-connected hybrid power system, the device including a controller configured to:

[0048] The energy function determination module is configured to apply disturbance to the state equation of the system when the grid-connected hybrid power system is at a steady-state equilibrium point, determine the branch mode energy function of the grid-connected wind turbine outlet, and determine the branch mode energy function of the grid-connected wind turbine outlet according to the active power-frequency control equation of the grid-side converter.

[0049] The oscillation characteristic analysis module is configured to superimpose the branch mode energy function of the grid-type wind turbine outlet with the branch mode energy function of the grid-type wind turbine outlet to obtain the mode energy curve, and to perform parameter identification on the mode energy curve to obtain the energy amplitude and frequency of different modes. Based on the energy amplitude of different modes, the participation degree of different modes in oscillation is determined.

[0050] Thirdly, embodiments of this application provide an electronic device, including: at least one processor and a memory; the memory stores computer execution instructions; the at least one processor executes the computer execution instructions stored in the memory, causing the at least one processor to execute the broadband oscillation characteristic analysis method for grid-connected hybrid power systems as described in the first aspect and various possible designs of the first aspect.

[0051] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions. When a processor executes the computer-executable instructions, it implements the method for analyzing the broadband oscillation characteristics of a grid-connected hybrid power system as described in the first aspect and various possible designs of the first aspect.

[0052] Fifthly, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the method for analyzing the broadband oscillation characteristics of a grid-connected hybrid power system as described in the first aspect and various possible designs of the first aspect.

[0053] The method, apparatus, equipment, and storage medium for analyzing broadband oscillation characteristics of grid-connected hybrid power systems provided in this application have at least the following beneficial effects:

[0054] 1. This application achieves decoupling analysis of the dynamic response of different control strategies by establishing branch mode energy functions for grid-connected and grid-connected wind turbines respectively, overcoming the limitation of traditional methods that make it difficult to distinguish the dynamic coupling effects of different new energy units.

[0055] 2. The superposition analysis of mode energy curves can cover a wide frequency range from subsynchronous to supersynchronous (typical range 0.1-100Hz), and can simultaneously capture the interaction between the fast dynamics of power electronic equipment and the slow dynamics of traditional synchronous machines, revealing the physical nature of complex multi-timescale oscillations.

[0056] 3. This application uses the mode energy amplitude as the participation index, which can directly quantify the nonlinear influence of each oscillation mode on the system stability boundary under disturbance.

[0057] 4. This application can accurately locate the energy transfer path of the dominant oscillation mode by utilizing the spatial distribution characteristics of the branch energy function, resulting in higher positioning accuracy.

[0058] 5. The mode energy amplitude-frequency characteristics obtained from parameter identification can be directly mapped to the controller parameter space (such as PLL bandwidth and virtual inertia coefficient), providing a quantitative design basis for impedance reshaping control of grid-type converters and shortening the parameter tuning cycle. Attached Figure Description

[0059] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0060] Figure 1 A flowchart illustrating an analytical method for broadband oscillation characteristics of a grid-connected hybrid power system provided in this application embodiment;

[0061] Figure 2 This is a diagram of the VSG control structure provided in the embodiments of this application;

[0062] Figure 3 A diagram of a grid-connected hybrid power system provided for embodiments of this application;

[0063] Figure 4 The energy amplitude diagram of the grid-type mode provided in the embodiments of this application;

[0064] Figure 5 The energy amplitude diagram of the mesh-and-grid mode provided in the embodiments of this application;

[0065] Figure 6 The mode energy curves provided in this application embodiment are for varying network control parameters.

[0066] Figure 7The following are mode energy comparison diagrams provided for embodiments of this application: (a) Mode energy curve of grid-connected wind turbine; (b) Mode energy curve of grid-connected-grid wind turbine.

[0067] Figure 8 The active power comparison diagrams provided for the embodiments of this application include: (a) active power curve of grid-connected type; and (b) active power curve of grid-connected type.

[0068] Figure 9 The active power spectrum diagrams provided for embodiments of this application include: (a) an active power spectrum diagram of a grid-connected wind turbine; and (b) an active power spectrum diagram of a grid-connected wind turbine.

[0069] Figure 10 Energy maps for different grid patterns provided in embodiments of this application;

[0070] Figure 11 Energy curves for different modes of grid-connected network configuration provided in embodiments of this application;

[0071] Figure 12 This is a structural diagram of a brain-like control network provided in an embodiment of this application.

[0072] The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0073] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0074] The collection, storage, use, processing, transmission, provision, and disclosure of financial data or user data involved in the technical solution of this application all comply with the provisions of relevant laws and regulations and do not violate public order and good morals.

[0075] It should be noted that in the embodiments of this application, certain software, components, models and other existing solutions in the industry may be mentioned. These should be regarded as exemplary and are only intended to illustrate the feasibility of implementing the technical solution of this application. However, it does not mean that the applicant has used or necessarily used the solution.

[0076] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0077] Example 1:

[0078] This application provides a method for analyzing the broadband oscillation characteristics of a grid-connected hybrid power system. The method includes the following steps S10-S20.

[0079] S10: When the grid-connected hybrid power system is at a steady-state equilibrium point, the system's state equation is disturbed to determine the branch mode energy function at the outlet of the grid-connected wind turbine, and the branch mode energy function at the outlet of the grid-connected wind turbine is determined according to the active power-frequency control equation of the grid-side converter.

[0080] In this embodiment, the purpose of step S10 is to construct the mode energy function of the grid-connected and grid-connected hybrid power system (i.e., the mode energy function of the branch outlet of the grid-connected wind turbine and the mode energy function of the branch outlet of the grid-connected wind turbine). For example, the active power dataset can be obtained based on system measurement information, and mode energy functions of the branch outlets of the grid-connected and grid-connected wind turbines can be constructed respectively.

[0081] Specifically, the energy function of the grid-connected hybrid power system model is constructed in the following manner:

[0082] When the system is at steady-state equilibrium, applying a small disturbance to its state equation yields the following equation:

[0083]

[0084] In the formula, Δx represents the derivative of the state variable; Δu represents the input variable; A, B, C, and D represent the state matrix, input matrix, output matrix, and feedforward matrix, respectively.

[0085] The general solution of the system's state equation is shown below:

[0086]

[0087] In the formula, Δx(t) represents the general solution of the state equation; ψ i , Let x and λ represent the left and right eigenvectors, respectively; x0 represents the initial value of the system state variable; λ i t represents the system characteristic value; t represents time.

[0088] The expression for the branch energy at this time is as follows:

[0089] V=∫(P ijs +ΔP ij )d(θ is +Δθ i )+∫(Q ijs +ΔQ ij )d(lnU is +ΔlnU i (3)

[0090] In the formula, Δ represents a small disturbance; s represents the steady-state value of the relevant electrical quantity; V represents the energy transmitted by the branch; P ijs ΔP represents the steady-state value of active power transmitted at nodes i and j; ij θ represents the increment of active power transmitted at nodes i and j; is θ represents the steady-state phase angle at node i; i U represents the phase angle at node i; i The voltage at node i is represented by d; d represents the integral sign.

[0091] Ignoring the reactive power component in equation (3), and taking transient quantities as the research object, the expression for the branch mode energy is as follows:

[0092] ΔV=∫ΔP ij d(Δθ i (4)

[0093] In the formula, ΔV represents the branch mode energy.

[0094] The electromagnetic power delivered by wind turbines using grid-connected and grid-connected control is shown in the following formula:

[0095] P e =U1U2(sinδ 12 ) / X 12 (5)

[0096] In equation (5): U1 represents the voltage amplitude at the new energy collection point, U2 represents the voltage amplitude at the PCC bus; δ 12 This represents the phase angle difference between the new energy collection point and the PCC bus; X 12 P represents the line reactance between the collection point and the PCC bus; e This indicates that the electromagnetic power delivered by new energy sources in a hybrid power system is composed of both grid-connected and grid-connected wind turbines.

[0097] P e =P e-GFL +P e-GFM (6)

[0098] In the formula, Pe-GFL Indicates the active power delivered by the grid-type wind turbine; P e-GFM This represents the active power delivered by a grid-connected wind turbine. If we take WT1 (Wind turbines) as the research object, we linearize its output active power:

[0099]

[0100] In equation (7), k δ This represents the synchronization coefficient of the wind turbine, equivalent to the synchronization coefficient k of a synchronous machine. s C dc ΔP represents the DC capacitance between the back-to-back converters; ΔP1 represents the active power output of the wind turbine after linearization; k0, k1, k2, k3, and k4 are all gain coefficients; ΔP u represents the active power output of the wind turbine; s represents the Laplace operator;

[0101] Based on the above derivation, the total energy generated by the grid-connected wind turbine (the branch mode energy function at the outlet of the grid-connected wind turbine) can be obtained as follows:

[0102]

[0103] In equation (8), ΔP es1 ΔP ed1 Let Δθ represent the incremental forms of the synchronous and damped components of the active power, respectively. es1 , Δθ es1 These represent the incremental forms of the synchronous and damping components of the phase angle, respectively; ΔV p-GFL This represents the branch mode energy function at the outlet of the grid-type wind turbine.

[0104] In the VSG control mode, the active power-frequency control equation of the grid-side converter is as follows:

[0105]

[0106] In the formula, J represents the moment of inertia; P ref Indicates the active power reference value; P represents active power; ω ref ω represents the rotor angular velocity reference value; D represents the damping coefficient; θ represents the shaft torsion angle.

[0107] From equation (9), the active power delivered by the grid-type wind turbine can be obtained as shown in the following equation:

[0108] P e-GFM =P ref -(Jω+D)(ω-ω ref (10)

[0109] In equation (10), P e-GFM This indicates the active power delivered by the grid-type wind turbine.

[0110] Linearizing equation (10), we obtain the following formula for the incremental active power delivered by the grid-type wind turbine:

[0111] ΔP e-GFM =-(JΔω+D)Δω (11)

[0112] Based on the above derivation, the mode energy function of the outlet branch of the grid-type wind turbine can be obtained as follows:

[0113] ΔV p-GFM =∫ΔP e-GFM dΔθ (12)

[0114] In equation (12), ΔV e-GFM The mode energy function ΔP represents the output branch of a grid-type wind turbine. e-GFM This indicates the increase in active power delivered by a grid-type wind turbine.

[0115] Linearizing the second formula in equation (9) and substituting it into equation (12), we can obtain the mode energy expression for the outlet branch of the grid-type wind turbine (the mode energy function of the outlet branch of the grid-type wind turbine):

[0116]

[0117] The energy function constructed by equation (13) is the output energy of the grid-connected wind turbine. This equation can be used to quantify the participation of the grid-connected wind turbine in the oscillation mode of the grid-connected hybrid power system, and has covered the energy components corresponding to different modes. Then, the parameter identification algorithm can be used to identify all the energy components participating in the oscillation.

[0118] S20: The branch mode energy function at the outlet of the grid-type wind turbine is superimposed with the branch mode energy function at the outlet of the grid-type wind turbine to obtain the mode energy curve. The parameters of the mode energy curve are identified to obtain the energy amplitude and frequency of different modes. Based on the energy amplitude of different modes, the participation degree of different modes in the oscillation is determined.

[0119] In step S20 of this embodiment, the Prony-LM (Levenberg-Marquardt) algorithm can be used to identify the obtained mode energy, obtain the mode energy distribution in different frequency bands, and then determine the degree of participation of different modes in the broadband oscillation of the system, and finally determine the dominant oscillation mode.

[0120] Specifically, based on the derivation process of step S10, it can be seen that equation (8) can be used to represent the branch mode energy of the grid-connected wind turbine outlet based on network quantity measurement, and equation (13) can be used to represent the branch mode energy of the grid-connected wind turbine outlet. In order to explore the influence law of grid-connected control on the broadband oscillation characteristics of the system, this embodiment superimposes equations (8) and (13) to obtain the influence law of grid-connected control on the hybrid power system (characterized by the mode energy curve), and performs online parameter identification on the obtained mode energy curve. Among them, the identification method adopts the Prony-LM method, which is a signal identification-optimization method: the Prony algorithm can be used to obtain the initial values ​​of the identification parameters under different modes, and then the LM method is used to complete the fast iteration and optimization.

[0121] Example 2:

[0122] This embodiment proposes an analytical method for broadband oscillation characteristics of a grid-connected hybrid power system based on network energy. Starting from the grid-connected hybrid power system and grid-connected control, it constructs a model of the grid-connected hybrid power system, builds the mode energy function of the grid-connected hybrid power system, and determines its influence on the system's broadband oscillation. The specific implementation principle of the method proposed in this embodiment has been described in Embodiment 1, and therefore will not be repeated here. This method can be implemented by the following steps:

[0123] Step 1: Based on the system measurement information, obtain the active power dataset and construct the mode energy functions for the outlet branches of the grid-type and grid-type wind turbines respectively.

[0124] Step 2: Use the Prony-LM (Levenberg-Marquardt) algorithm to identify the obtained mode energy, obtain the mode energy distribution in different frequency bands, and then determine the degree of participation of different modes in the system's broadband oscillation, and finally determine the dominant oscillation mode.

[0125] Step 3: Investigate the influence of grid-based control on broadband oscillations in hybrid power systems, and construct a grid-based hybrid power system using MATLAB / Simulink to verify the feasibility of the proposed method.

[0126] It should be noted that steps 1 and 2 correspond to steps S10 and S20 of the method proposed in Embodiment 1.

[0127] Specifically, in step 2, to determine the influence of grid-type control on the broadband oscillation of the hybrid power system, equations (8) and (13) are superimposed, and the mode energy distribution before and after grid-type wind turbine grid connection is compared. Figure 7It can be seen that after grid-connected wind turbines are connected to the grid, the original mode of energy distribution of the hybrid power system is disrupted. Since the wind turbine is taken as the research object, the slope of the energy function of the wind turbine outlet branch is greater than 0 at this time, that is, the wind turbine is emitting energy and the energy is dissipated by the infinite system. Therefore, it can be inferred that the grid connection of grid-connected wind turbines will disrupt the stability of the grid-connected hybrid power system.

[0128] The energy distribution of the wind turbine outlet branch under two operating conditions—grid-connected and grid-connected-structured—was sampled at equal intervals, and parameter identification was performed. The entire identification process is as follows: Figure 1 As shown, the amplitude and frequency of the oscillation energy corresponding to each mode can be obtained. The parameter identification results for each mode are shown in Tables 1 and 2. Obviously, there are 5 oscillation modes in Table 1 and 7 oscillation modes in Table 2. The mode with the largest and smallest energy amplitudes are selected as the research objects for comparison, and the mode energy amplitudes are as follows: Figure 4 , Figure 5 As shown.

[0129] Table 1. Energy identification results based on network pattern

[0130]

[0131] Table 2 Energy identification results of the network-networked model

[0132]

[0133] from Figure 4 As can be seen from the data, among the network-type modes, mode 4 has the highest mode energy, meaning mode 4 is the dominant oscillation mode, while modes 2 and 3 have the lowest modes energy and the lowest participation in the oscillation; from... Figure 5 As can be seen from the data, among the network-structured network modes, mode 5 has the highest mode energy, which is the dominant oscillation mode. Modes 2 and 7 have the lowest energy amplitude and the lowest participation in the oscillation.

[0134] exist Figure 2 In this model, D (virtual damping coefficient) is equivalent to the damping effect of the synchronous machine, and J (virtual inertia constant) is equivalent to the inertia of the synchronous machine, jointly determining the direction of the VSG control mode. Therefore, it is necessary to study their influence on system oscillation. A simulation system such as [example system name] is built in the simulation software. Figure 3 The simulation example shown applies a small disturbance at the 3rd second, sets different key control parameters for different network configurations, and compares the system mode energy curves under different operating conditions with different key control parameters. Figure 6 As shown.

[0135] from Figure 6It is readily apparent that as D increases and J decreases, the slope of the mode energy curve gradually decreases. According to Lyapunov's second theorem, when a small disturbance is applied to the system, the virtual damping coefficient will provide damping for the system. The higher the level of damping provided, the lower the amplitude of system oscillations, and the easier it is to restore stability.

[0136] To investigate the impact of grid-connected registration on broadband oscillations of the system before and after grid connection, a network was constructed... Figure 3 In the example, the same small disturbance is applied, and the two scenarios of grid-connected and grid-connected hybrid power systems are compared. The influence of grid-connected wind turbines on system stability under the two operating conditions can be obtained as follows: Figure 7 , 8 As shown in Figure 9, from Figure 7 , 8 As can be seen from point 9, after the grid-connected wind turbines are connected to the grid, the system's modal energy distribution begins to fluctuate, causing the system's active power to change from damped oscillations to constant-amplitude oscillations. Figure 9 It is easy to see that the grid connection of grid-connected wind turbines reduces the system's oscillation frequency; that is, the connection of grid-connected wind turbines will cause low-frequency oscillation problems in the system. Furthermore... Figure 9 As shown in (a), the active power oscillation frequency of the grid-connected wind turbine is 27.1 Hz. Table 1 shows that the energy frequency of the dominant oscillation mode 4 in the grid-connected mode is 54.18 Hz, which is approximately twice the active power oscillation frequency. The active power oscillation frequency in the grid-connected wind turbine is 8.6 Hz. The energy frequency of the dominant oscillation mode 5 in Table 2 is 17.32 Hz, which is also approximately twice the active power oscillation frequency. This demonstrates the effectiveness of the method proposed in this application.

[0137] against Figure 7 In (a), the Prony-LM method was used for parameter identification. Since mode 4 has the highest energy, while modes 2 and 3 have the lowest amplitudes, the energy of these three modes was compared, and the results are as follows. Figure 10 As shown, by Figure 10 It can be seen that mode 4 has the largest energy component oscillation amplitude, meaning mode 4 is the dominant oscillation mode. Modes 2 and 3 have smaller energy amplitudes and contribute the least to the oscillation, proving the correctness of the previous analysis; similarly... Figure 7 In (b), mode 5 has the highest energy amplitude and is the dominant oscillation mode, while modes 2 and 7 contribute the least to the oscillation. Therefore, a comparative analysis of the energy components of these three modes is conducted again, and the results are as follows: Figure 11 As shown.

[0138] Depend on Figure 11It can be seen that after frequency division of the energy, among the energy components of different modes, mode 5 has the largest energy fluctuation amplitude, while modes 2 and 7 have the smallest fluctuation amplitude. That is, mode 5 is the dominant oscillation mode, while modes 2 and 7 contribute the least to the oscillation, and therefore have the smallest energy amplitude, which once again proves the correctness of the previous analysis.

[0139] Example 3:

[0140] This application also provides a device for analyzing the broadband oscillation characteristics of a grid-connected hybrid power system, such as... Figure 12 As shown, the broadband oscillation characteristic analysis device for the grid-connected hybrid power system includes:

[0141] The energy function determination module 1201 is configured to apply disturbance to the state equation of the system when the grid-connected hybrid power system is at a steady-state equilibrium point, determine the branch mode energy function of the grid-connected wind turbine outlet, and determine the branch mode energy function of the grid-connected wind turbine outlet according to the active power-frequency control equation of the grid-side converter.

[0142] The oscillation characteristic analysis module 1202 is configured to superimpose the branch mode energy function of the grid-type wind turbine outlet with the branch mode energy function of the grid-type wind turbine outlet to obtain the mode energy curve, and to perform parameter identification on the mode energy curve to obtain the energy amplitude and frequency of different modes. Based on the energy amplitude of different modes, the participation degree of different modes in oscillation is determined.

[0143] This application provides an electronic device. The electronic device may include a processor and a memory, wherein the processor and the memory can communicate; exemplarily, the processor and the memory communicate via a communication bus.

[0144] The processor executes computer execution instructions stored in memory, causing the processor to perform the schemes in the above embodiments. The processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0145] The communication bus can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The system bus can be divided into address bus, data bus, control bus, etc. Transceivers are used to enable communication between database access devices and other computers (e.g., clients, read-write libraries, and read-only libraries). Memory may include random access memory (RAM) and may also include non-volatile memory.

[0146] The electronic device provided in this application embodiment can be the terminal device described in the above embodiments.

[0147] This application also provides a computer-readable storage medium storing computer instructions. When the computer instructions are executed on a computer, the computer performs the technical solution of the above-described method for analyzing the broadband oscillation characteristics of a grid-connected hybrid power system.

[0148] This application also provides a computer program product, which includes a computer program stored in a computer-readable storage medium. At least one processor can read the computer program from the computer-readable storage medium. When the at least one processor executes the computer program, it can implement the technical solution of the broadband oscillation characteristic analysis method of the grid-connected hybrid power system described in the above embodiments.

[0149] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or modules, and may be electrical, mechanical, or other forms.

[0150] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to implement the solution of this embodiment according to actual needs.

[0151] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing unit, or each module can exist physically separately, or two or more modules can be integrated into one unit. The unit composed of the above modules can be implemented in hardware or in the form of hardware plus software functional units.

[0152] The integrated modules described above, implemented as software functional modules, can be stored in a computer-readable storage medium. These software functional modules, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods of the various embodiments of this application.

[0153] It should be understood that the aforementioned processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly manifested as being executed by a hardware processor, or executed by a combination of hardware and software modules within the processor.

[0154] The memory may include high-speed RAM, and may also include non-volatile storage (NVM), such as at least one disk storage device, and may also be a USB flash drive, external hard drive, read-only memory, disk or optical disc, etc.

[0155] Buses can be Industry Standard Architecture (ISA) buses, Peripheral Component Interconnect (PCI) buses, or Extended Industry Standard Architecture (EISA) buses, etc. Buses can be categorized into address buses, data buses, control buses, etc.

[0156] The aforementioned storage medium can be implemented from any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The storage medium can be any available medium accessible to general-purpose or special-purpose computers.

[0157] An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Alternatively, the storage medium can be an integral part of the processor. The processor and storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and storage medium can exist as discrete components in an electronic control unit or main control device.

[0158] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0159] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for analyzing broadband oscillation characteristics of a hybrid power system of a follow-the-sun-grid-forming type, characterized by comprising: The method comprises: When the grid-following-grid-constructing hybrid power system is at a steady-state equilibrium point, a disturbance is applied to a state equation of the system, a branch mode energy function at an outlet of a grid-following wind turbine is determined, and a branch mode energy function at an outlet of a grid-constructing wind turbine is determined according to an active power-frequency control equation of a grid-side converter; The branch mode energy function at the outlet of the grid-following wind turbine and the branch mode energy function at the outlet of the grid-constructing wind turbine are superimposed to obtain a mode energy curve, and parameter identification is performed on the mode energy curve to obtain energy amplitudes and frequencies of different modes, and the participation degrees of the different modes in oscillation are determined according to the energy amplitudes of the different modes. The branch mode energy function at the outlet of the grid-following wind turbine is: where ΔP es1 , ΔP ed1 represent the incremental form of the synchronous and damping components of real power, respectively; Δθ es1 , Δθ es1 represent the incremental form of the synchronous and damping components of phase angle, respectively; ΔV p-GFL represents the branch pattern energy function at the outlet of grid-following wind turbines; and t represents time. The branch mode energy function at the outlet of the grid-constructing wind turbine is: where ΔV e-GFM represents the mode energy function of the network-structured fan outlet branch; ΔP e-GFM represents the active power increment delivered by the network-structured fan; J represents the moment of inertia; ω represents the rotor angular velocity; D represents the damping coefficient; and θ represents the shaft torsion angle. 2.The method of claim 1, wherein, When the grid-following-grid-constructing hybrid power system is at a steady-state equilibrium point, a disturbance is applied to a state equation of the system, a branch mode energy function at an outlet of a grid-following wind turbine is determined, and a branch mode energy function at an outlet of a grid-constructing wind turbine is determined according to an active power-frequency control equation of a grid-side converter; When the grid-following-grid-constructing hybrid power system is at a steady-state equilibrium point, a disturbance is applied to a state equation of the system, and the following is obtained: wherein denotes a derivative of a state variable; Δx denotes a state variable; Δu denotes an input variable; A, B, C, and D denote a state matrix, an input matrix, an output matrix, and a feedforward matrix, respectively; The general solution form of the state equation of the system is as follows: where Δx(t) represents the general solution of the state equation; ψ i , represent the left and right eigenvectors, respectively; x0represents the initial value of the system state variable; λ i represents the system eigenvalue; After the disturbance is applied to the state equation of the system, the expression of the branch energy is determined as follows: V = ∫(P ijs + ΔP ij )d(θ is + Δθ i ) + ∫(Q ijs + ΔQ ij )d(lnU is + ΔlnU i ) (3) where Δ represents a small disturbance; s represents a steady state value of a relevant electrical quantity; V represents energy transmitted by a branch; P ijs represents a steady state value of active power transmitted on i, j nodes; ΔP ij represents an increment of active power transmitted on i, j nodes; θ is represents a steady state value of phase angle on i node; θ i represents a phase angle on i node; U i represents a voltage on i node; d represents an integral symbol; Based on the expression of the branch energy, the transient state is taken as the research object, and the expression of the branch mode energy is obtained as shown in the following formula: AV = ∫ΔP ij d(Δθ i ) (4) In the formula, ΔV represents the branch mode energy. The electromagnetic power sent by the wind turbine with the grid-following type and the grid-constructing type is determined by the following formula: P e = U1U2(sin δ 12 ) / X 12 (5) In the formula, U1 represents the voltage amplitude of the new energy collection point, U2 represents the voltage amplitude of the PCC bus; δ 12 represents the phase angle difference between the new energy collection point and the PCC bus; X 12 represents the line reactance between the collection point and the PCC bus; P e represents the electromagnetic power sent out by the new energy in the hybrid power system, which is composed of grid-following wind turbines and grid-forming wind turbines: P e = P e-GFL + P e-GFM (6) In the formula, P e-GFL represents the active power sent out by grid-connected wind turbines; P e-GFM represents the active power sent out by grid-connected wind turbines; The active power output by the wind turbine is linearized to obtain the following formula: wherein k δ represents the synchronization coefficient of the wind turbine; C dc represents the DC capacitor value between the back-to-back converters; ΔP1 represents the active power of the wind turbine output after linearization; k0, k1, k2, k3, k4 are all gain coefficients; ΔP u represents the active power of the wind turbine output; s represents the Laplace operator; The branch mode energy function at the outlet of the grid-following wind turbine is determined as follows. 3.The method of claim 2, wherein, The active power-frequency control equation of the grid-side converter is expressed as follows: In the formula, P ref represents the active power reference value; P represents the active power; ω ref represents the rotor angular velocity reference value.

4. The method of claim 3, wherein the method is characterized by, According to the active power-frequency control equation of the grid-side converter, the branch mode energy function at the outlet of the grid-constructing wind turbine is determined, and the active power sent by the grid-constructing wind turbine is obtained as shown in the following formula: The branch mode energy function at the outlet of the grid-constructing wind turbine is determined as shown in the following formula: P e-GFM = P ref -(Jω + D)(ω - ω ref ) (10) In the formula, P e-GFM represents the active power delivered by the network-forming fan. Linearizing equation (10) gives the incremental active power ΔP of the grid-connected wind turbine e-GFM As shown in the following equation: ΔP e-GFM = -(JΔω + D)Δω (11) The parameter identification of the mode energy curve is performed by using the Prony algorithm. ΔV p-GFM = ∫ΔP e-GFM dΔθ (12) In equation (9) Linearization is then applied to equation (12) to obtain the branch mode energy function at the outlet of the grid-type wind turbine. 5.The method of claim 1, wherein, According to the energy amplitudes of the different modes, the participation degrees of the different modes in oscillation are determined in the following manner: according to the sizes of the energy amplitudes, the participation degrees of the different modes in oscillation are determined, the larger the energy amplitude, the higher the participation degree of the corresponding mode in oscillation, and the mode with the largest energy amplitude is determined as the dominant oscillation mode. 6.The method of claim 1, wherein, The device comprises:

7. A device for analyzing a wideband oscillation characteristic of a hybrid power system of a follow-the-sun-grid-forming type, characterized by comprising: a wideband oscillation characteristic analysis unit configured to analyze a wideband oscillation characteristic of the hybrid power system of the follow-the-sun-grid-forming type. An energy function determination module is configured to, when the grid-following-grid-constructing hybrid power system is at a steady-state equilibrium point, apply a disturbance to a state equation of the system, determine a branch mode energy function at an outlet of a grid-following wind turbine, and determine a branch mode energy function at an outlet of a grid-constructing wind turbine according to an active power-frequency control equation of a grid-side converter; ​ The oscillation characteristic analysis module is configured to superimpose the branch mode energy function of the grid-following fan outlet and the branch mode energy function of the grid-forming fan outlet to obtain a mode energy curve, perform parameter identification on the mode energy curve to obtain energy amplitudes and frequencies of different modes, and determine participation degrees of different modes in oscillation according to the energy amplitudes of different modes; The branch mode energy function of the grid-following fan outlet is: where ΔP es1 , ΔP ed1 represent the incremental form of the synchronous and damping components of real power, respectively; Δθ es1 , Δθ es1 represent the incremental form of the synchronous and damping components of phase angle, respectively; ΔV p-GFL represents the branch pattern energy function at the outlet of grid-following wind turbines; and t represents time. The branch mode energy function of the grid-forming fan outlet is: where ΔV e-GFM represents the mode energy function of the network-structured fan outlet branch; ΔP e-GFM represents the active power increment delivered by the network-structured fan; J represents the moment of inertia; ω represents the rotor angular velocity; and D represents the damping coefficient.

8. An electronic device, comprising: The method comprises: a processor, and a memory connected with the processor in communication; the memory stores computer execution instructions; the processor executes the computer execution instructions stored in the memory to implement the grid-following-grid-forming hybrid power system wide-frequency oscillation characteristic analysis method according to any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer readable storage medium stores computer execution instructions, and the computer execution instructions are executed by the processor to implement the grid-following-grid-forming hybrid power system wide-frequency oscillation characteristic analysis method according to any one of claims 1-6.

10. A computer program product, characterised in that, The computer program is executed by the processor to implement the grid-following-grid-forming hybrid power system wide-frequency oscillation characteristic analysis method according to any one of claims 1-6.

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