A method, system and medium for offshore wind turbine electrical coupling frequency response analysis

Abstract

The present application relates to the technical field of wind power grid-connected frequency response, and particularly relates to a kind of offshore wind turbine electromechanical coupling frequency response analysis method, system and medium, method includes: obtaining offshore multiple grid-connected receiving end wind power operating parameter;Based on operating parameter, the system frequency response relationship of system frequency variation under power disturbance is established;Establish the electromechanical coupling relationship between system frequency variation, rotor motion state variable and wind turbine response power, and construct the nonlinear parameterization equivalent model of fan mechanical power based on rotor motion state variable;Based on the linearization processing of electromechanical coupling relationship of nonlinear parameterization equivalent model, and eliminate rotor motion state variable, obtain wind power response analysis relationship;Wind power response analysis relationship is substituted into system frequency response relationship, and system frequency analysis model is obtained.The present application effectively solves the problem that the existing wind power frequency response model ignores the internal electromechanical coupling dynamics of wind turbine, which leads to the distortion of system frequency response analysis result.

Description

Technical Field

[0001] This invention relates to the field of wind power grid connection frequency response technology, and in particular to a method, system and medium for analyzing the frequency response of offshore wind turbine coupling. Background Technology

[0002] As the scale of offshore wind power grid connection expands, wind turbines need to support system power imbalances through power control and rotor kinetic energy release when participating in grid frequency response. Accurately characterizing the internal electromechanical dynamics of wind turbines is fundamental to analyzing system frequency changes and setting frequency regulation parameters. Existing technologies such as CN116093970A establish a doubly-fed induction generator (DFIG) frequency response model and combine it with speed protection for frequency regulation control, while CN115603334A analyzes wind turbine droop control and frequency dynamic characteristics through a system frequency response model.

[0003] However, existing solutions typically simplify or separate the relationships between wind turbine mechanical power, maximum power point tracking control, rotor kinetic energy release, and response power, making it difficult to establish a direct analytical relationship between the internal electromechanical state of the wind turbine and the system frequency. This results in the system frequency response model failing to accurately reflect the power attenuation and recovery dynamics during frequency regulation. Therefore, there is an urgent need for a system frequency analytical modeling method that can account for the internal electromechanical coupling dynamics of the wind turbine.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] This invention provides a method, system, and medium for analyzing the frequency response of offshore wind turbine coupling, which can effectively solve the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An analytical method for the electrical coupling frequency response of offshore wind turbines, the method comprising: Obtain operating parameters of offshore multi-grid-connected receiving-end wind power systems; Based on the aforementioned operating parameters, a system frequency response relationship is established to characterize the system frequency change under power disturbance. Establish the electromechanical coupling relationship between the system frequency change, rotor motion state quantity and wind turbine response power, and construct a nonlinear parameterized equivalent model of wind turbine mechanical power based on the rotor motion state quantity; The electromechanical coupling relationship is linearized based on the nonlinear parameterized equivalent model, and the rotor motion state quantity is eliminated to obtain the wind power response analytical relationship between the wind turbine response power and the system frequency change. Substituting the wind power response analytical relationship into the system frequency response relationship, a system frequency analytical model considering the electromechanical coupling dynamics within the wind turbine is obtained.

[0007] Furthermore, the operating parameters include system parameters, synchronous generator parameters, and wind turbine parameters; The system parameters include the power ratio of synchronous generator units, wind power grid connection penetration rate, system equivalent inertia time constant, and load damping coefficient. The system frequency response relationship includes the coupling relationship between the system frequency change, system disturbance power, synchronous generator response power and wind turbine response power; The synchronous unit response power is determined by the synchronous unit frequency response model that retains the reheat dynamic link.

[0008] Furthermore, the rotor motion state quantity is the change in the mechanical angular velocity of the wind turbine rotor; the nonlinear parameterized equivalent model uses a function with the mechanical angular velocity of the wind turbine rotor as the independent variable to characterize the mechanical power of the wind turbine; the model parameters of the nonlinear parameterized equivalent model are determined based on the wind turbine impeller parameters, gearbox parameters, generator parameters, and real-time wind speed.

[0009] Furthermore, the nonlinear parameterized equivalent model is applicable to wind turbines operating in maximum power point tracking mode and with the pitch angle remaining at zero. The wind turbine provides the wind turbine response power by releasing rotor kinetic energy, and does not adopt a load reduction operation mode or a pitch reserve mode.

[0010] Furthermore, the electromechanical coupling relationship couples maximum power point tracking control, virtual inertia control, and droop control; the linearization process includes ignoring higher-order terms of the rotor motion state variables, and linearizing the maximum power point tracking control output power and the equivalent mechanical power determined by the nonlinear parameterized equivalent model, respectively.

[0011] Furthermore, the analytical relationship of wind power response is obtained, including: Based on the electromechanical coupling relationship after linearization, a first analytical relationship is determined between the rotor motion state quantity and the system frequency change quantity. Based on the rotor kinetic energy release process, a second analytical relationship is determined between the wind turbine response power and the rotor motion state quantity; Substitute the first analytical relation into the second analytical relation and eliminate the rotor motion state quantity to obtain the wind power response analytical relation.

[0012] Furthermore, frequency response performance analysis is performed based on the system frequency analytical model, including: The system frequency analytical model is compared with the traditional simplified model that ignores the internal electromechanical coupling dynamics of the wind turbine to determine the deviation between the system frequency minimum point and the frequency recovery rate. By comparing the wind turbine response power corresponding to the system frequency analytical model and the traditional simplified model, the active power output attenuation characteristics and reverse power absorption characteristics during the frequency regulation process are determined. The system frequency analytical model is compared with the refined simulation model to determine the model errors of the frequency drop rate, the system frequency minimum point, and the frequency recovery trajectory.

[0013] Furthermore, based on the system frequency analysis model, the frequency modulation control parameters are configured collaboratively, including: By changing the virtual inertia control parameters, the effects of the virtual inertia control parameters on the initial frequency change rate of the disturbance, the lowest point of the system frequency, and the frequency recovery overshoot were determined. By changing the droop control parameters, the effects of the droop control parameters on the frequency descent rate, the system frequency minimum point, and the frequency recovery overshoot are determined. Based on the influence of the virtual inertia control parameters and the droop control parameters, and in conjunction with the releaseable rotor kinetic energy and rotor speed safety constraints of the wind turbine, the frequency regulation control parameters are determined.

[0014] An analytical system for the electrical coupling frequency response of offshore wind turbines, the system comprising: The operating parameter acquisition module acquires the operating parameters of offshore multi-grid-connected receiving-end wind power systems. The frequency response construction module establishes a system frequency response relationship based on operating parameters to characterize the system frequency change under power disturbances. An electromechanical coupling equivalent module is used to establish the electromechanical coupling relationship between the system frequency change, rotor motion state quantity and wind turbine response power, and a nonlinear parameterized equivalent model of wind turbine mechanical power is constructed based on the rotor motion state quantity. The wind power response analysis module linearizes the electromechanical coupling relationship based on a nonlinear parameterized equivalent model and eliminates rotor motion state variables to obtain the wind power response analysis relationship between the wind turbine response power and the system frequency change. The system frequency analysis module substitutes the wind power response analysis relationship into the system frequency response relationship to obtain a system frequency analysis model that takes into account the internal electromechanical coupling dynamics of the wind turbine.

[0015] A computer-readable storage medium storing a computer program, the computer program including program instructions that, when executed by a processor, can implement the aforementioned method for analyzing the electrical coupling frequency response of offshore wind turbines.

[0016] The technical solution of this invention can achieve the following technical effects: By acquiring the operating parameters of offshore multi-grid-connected wind power systems, the system frequency response relationship and the electromechanical coupling relationship of wind turbines are constructed sequentially. The mechanical power of the wind turbines is subjected to nonlinear parameterization equivalence and linearization processing, and the rotor motion state variables are eliminated. Then, the analytical relationship of wind power response and the system frequency analytical model that takes into account the internal electromechanical coupling dynamics of the wind turbine are established. This effectively solves the problem that the existing wind power frequency response model ignores the internal electromechanical coupling dynamics of the wind turbine, resulting in the distortion of the system frequency response analytical results.

[0017] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart illustrating the analytical method for the electrical coupling frequency response of offshore wind turbines; Figure 2 This is a schematic diagram of the frequency response model of a wind power grid-connected system. Figure 3 A schematic diagram of the detailed frequency response model of wind power; Figure 4 Flowchart of electromechanical dynamic analytical modeling and performance analysis method; Figure 5 This is a graph showing the frequency response of a traditional frequency response model system. Figure 6 A detailed frequency response model of the system, including its frequency response curves. Figure 7 A comparison chart of the frequency response power of wind turbines using traditional frequency response models; Figure 8 A detailed comparison chart of the frequency response power of wind turbine generators using frequency response models; Figure 9 This is a verification diagram for the system frequency model; Figure 10 Virtual inertia coefficient k fd Schematic diagram of the impact; Figure 11Sag coefficient k fp A diagram illustrating the impact. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Example 1; like Figure 1 As shown, this application provides an analytical method for the electrical coupling frequency response of offshore wind turbines, the method comprising: S10: Obtain the operating parameters of offshore multi-grid-connected receiving-end wind power systems; S20: Based on operating parameters, establish a system frequency response relationship to characterize the system frequency change under power disturbance; S30: Establish the electromechanical coupling relationship between the system frequency change, rotor motion state quantity and wind turbine response power, and construct a nonlinear parameterized equivalent model of wind turbine mechanical power based on the rotor motion state quantity; S40: The electromechanical coupling relationship is linearized based on the nonlinear parameterized equivalent model, and the rotor motion state quantity is eliminated to obtain the analytical relationship between the wind turbine response power and the system frequency change. S50: Substitute the wind power response analytical relationship into the system frequency response relationship to obtain the system frequency analytical model that takes into account the internal electromechanical coupling dynamics of the wind turbine.

[0023] Specifically, this embodiment provides an analytical method for the electro-mechanical coupling frequency response of offshore wind turbines, which is applicable to the operation scenario where multiple offshore wind farms are connected to the receiving-end power grid through multiple transmission channels; First, operating parameters of offshore multi-grid-connected receiving-end wind power systems are obtained from the power grid dispatching system, wind farm monitoring system, wind turbine controller, and equipment parameter database. These operating parameters include system equivalent inertia, load damping, wind power grid connection penetration rate, synchronous turbine operating parameters, wind turbine structural parameters, wind turbine operating status, frequency regulation control parameters, and power disturbance information. Parameters from different wind farms and transmission channels are standardized and aggregated to form the parameter set required for system frequency response analysis. Secondly, based on the system power balance relationship and equivalent inertial response process, a system frequency response relationship is established between power disturbance, synchronous generator power response, wind turbine power response and system frequency change; the system frequency response relationship is used to describe the common impact of the power regulation process of various power sources on system frequency change after the system experiences load change or power generation change; Subsequently, based on the power control process, rotor motion process, and electromechanical energy conversion process of the wind turbine, an electromechanical coupling relationship is established between the system frequency change, rotor motion state quantity, and wind turbine response power. The rotor motion state quantity is used to characterize the rotor speed change when the wind turbine participates in the frequency response. To address the nonlinear relationship between the wind turbine mechanical power and the rotor motion state quantity, a nonlinear parameterized equivalent model of the wind turbine mechanical power is constructed based on the wind turbine structural parameters, operating wind speed, and rotor operating state. This nonlinear parameterized equivalent model can characterize the dynamic changes in wind energy capture capability and mechanical power during frequency regulation. Then, taking the stable operating state of the wind turbine before the disturbance as the linearization benchmark, the nonlinear parameterized equivalent model and electromechanical coupling relationship are locally linearized, retaining the main first-order dynamic components that affect the frequency response. The linearized mechanical power relationship, power control relationship and rotor motion relationship are jointly solved to obtain the analytical relationship between the rotor motion state quantity and the system frequency change quantity. By substituting variables to eliminate the rotor motion state quantity, the analytical relationship between the wind turbine response power and the system frequency change quantity is obtained. Finally, the wind power response analytical relationship is substituted into the system frequency response relationship to organize and simplify the system frequency response relationship, thereby obtaining a system frequency analytical model that takes into account the electromechanical coupling dynamics within the wind turbine. The system frequency analytical model is used to calculate the system frequency change trajectory after power disturbance and provides a model basis for the frequency change rate, frequency minimum point, frequency recovery process, and frequency regulation control parameter influence analysis.

[0024] The technical solution of this invention obtains the operating parameters of offshore multi-grid-connected wind power systems, sequentially constructs the system frequency response relationship and the electromechanical coupling relationship of wind turbine units, performs nonlinear parameterization equivalence and linearization processing on the mechanical power of wind turbines and eliminates rotor motion state variables, and then establishes the wind power response analytical relationship and the system frequency analytical model that takes into account the internal electromechanical coupling dynamics of wind turbine units. This effectively solves the problem that the existing wind power frequency response model ignores the internal electromechanical coupling dynamics of wind turbine units, resulting in the distortion of the system frequency response analytical results.

[0025] Furthermore, operating parameters include system parameters, synchronous generator parameters, and wind turbine parameters; System parameters include the power ratio of synchronous generator units, wind power grid connection penetration rate, system equivalent inertia time constant, and load damping coefficient; The system frequency response relationship includes the coupling relationship between system frequency change, system disturbance power, synchronous generator response power, and wind turbine response power; The response power of the synchronous generator unit is determined by the frequency response model of the synchronous generator unit with reheat dynamics retained.

[0026] As a preferred embodiment of the above, the frequency response model of the wind power grid-connected system constructed in this scheme is as follows: Figure 2 and Figure 3 As shown, the model is divided into two main parts: the synchronous generator frequency response module and the wind turbine frequency response module. Specifically, the physical definitions and configuration methods of each state variable and system parameter in this model are as follows: Δ f ( s ) represents the system frequency change, used to characterize the dynamic frequency shift of the power grid after a disturbance; Δ P d Δ represents the system load disturbance power, corresponding to external disturbance inputs such as sudden changes in grid load and fluctuations in new energy output; P th The dynamic output power of the synchronous generator set is used to demonstrate the frequency regulation support capability of a traditional synchronous generator set; Δ P w This model represents the dynamic output power of wind turbines, characterizing the power response characteristics of wind power participating in system frequency regulation. Simultaneously, it incorporates key system configuration ratios and state parameters to achieve precise scenario adaptation. d th The power ratio of synchronous generator units is used to quantify the grid connection ratio of traditional synchronous power sources; d w , which represents the wind power grid connection penetration rate, used to characterize the proportion of wind power access in offshore multi-grid receiving-end systems; H sys It is the system's equivalent inertia time constant, which comprehensively reflects the inertial support level of the entire grid-connected system; D The load damping coefficient is used to characterize the effect of load-side damping on suppressing system frequency oscillations. Combination Figure 3 It can be seen that frequency regulation of wind turbine units is a dynamic process involving multiple internal control links and electromechanical variable coupling, and is not a simple linear superposition of virtual inertia control and droop control. In the generation of unit power control commands, the wind turbine converter output power reference command... P ref The frequency modulation process is not only subject to the regulation of virtual inertia control and droop control, but also to the strong coupling constraint of the unit's maximum power point tracking (MPPT) control. The three types of control elements jointly determine the power command output of the frequency modulation process, and the coupling relationship of each control element satisfies the following formula: (2); In the formula, k p This is the droop control coefficient; k d This refers to the virtual inertia control coefficient. s For the Laplace operator; ω This refers to the mechanical angular velocity of the fan rotor. P MPPT The basic power command output by the MPPT control module; k opt The optimal control coefficient for MPPT is uniquely determined by the inherent structural parameters of the wind turbine, such as the impeller, gearbox, and generator. Traditional wind turbine frequency response modeling methods oversimplify the unit's frequency regulation control mechanism, assuming an assumed unit frequency response power Δ P e The modeling method is determined solely by the linear relationship between virtual inertia control and droop control, completely severing the coupling relationship between MPPT control and the frequency regulation dynamic process. It assumes that the unit's frequency regulation power will inevitably continue to increase when the system frequency deviation increases. At the same time, this modeling method does not consider the dynamic constraint effect of MPPT control in the entire frequency regulation process, and cannot truly reproduce the power dynamic response characteristics of the unit under the actual frequency regulation conditions. Establish the frequency response relationship of the wind power grid-connected system: Based on the relationship between the frequency response power of synchronous generator units, the frequency response power of wind turbines, and the load disturbance power, a frequency response model for the system frequency change is established: (3); In the formula, s For the Laplace operator; The frequency-active power transfer function represents the frequency response of a synchronous generator unit; for By simplifying the modeling, treating the synchronous units in the system as reheat turbine units, and retaining the larger reheat time constant, we obtain: (4); In the formula, This refers to the power percentage of the high-pressure cylinder. The reheat time constant is This is the droop factor of the synchronous machine; due to load disturbance power Invariable quantity with system frequency Therefore, when constructing the analytical expression for the system frequency response, the power frequency response of the wind turbine is established. With frequency change The relationship between them.

[0027] Furthermore, the rotor motion state quantity is the change in the mechanical angular velocity of the wind turbine rotor; the nonlinear parameterized equivalent model uses a function with the mechanical angular velocity of the wind turbine rotor as the independent variable to characterize the mechanical power of the wind turbine; the model parameters of the nonlinear parameterized equivalent model are determined based on the wind turbine impeller parameters, gearbox parameters, generator parameters and real-time wind speed.

[0028] Furthermore, the nonlinear parameterized equivalent model is applicable to wind turbines operating in maximum power point tracking mode and with the pitch angle remaining at zero. The wind turbine provides the wind turbine response power by releasing rotor kinetic energy, without adopting a load reduction operation mode or pitch reserve mode.

[0029] Furthermore, the electromechanical coupling relationship couples the maximum power point tracking control, virtual inertia control, and droop control; the linearization process includes ignoring higher-order terms of rotor motion state variables and linearizing the output power of the maximum power point tracking control and the equivalent mechanical power determined by the nonlinear parameterized equivalent model, respectively.

[0030] Furthermore, obtaining the analytical relationship of wind power response includes: Based on the linearized electromechanical coupling relationship, the first analytical relationship between the rotor motion state quantity and the system frequency change quantity is determined. Based on the rotor kinetic energy release process, a second analytical relationship between the wind turbine response power and the rotor motion state variables is determined. Substituting the first analytical relation into the second analytical relation and eliminating the rotor motion state variables, we obtain the analytical relation for wind power response.

[0031] As a preferred embodiment of the above, a relationship is established between the frequency change and the rotor mechanical angular velocity change: By treating the electromechanical conversion link as an intermediate link connecting the rotor motion state of the fan and the electromagnetic power response, and establishing relevant relationships, the frequency change is determined. With the change in rotor mechanical angular velocity Relationships in the complex frequency domain: (5); In the formula, H w The equivalent inertia time constant of the wind turbine; The initial rotor mechanical angular velocity of the wind turbine before it participates in frequency regulation; P m The mechanical power input to the transmission system after the wind turbine captures wind energy; Δ ω ( s ) represents the change in rotor mechanical angular velocity Δ ω Representation in the complex frequency domain; as can be seen from equation (4), in establishing and When analyzing the relationship, the mechanical power of the wind turbine The expression is quite complex, and there are multiple expressions in equation (4). The higher-order terms; therefore, it is necessary to make the mechanical power of the wind turbine equivalent and simplify the model. Construct an equivalent model of the wind turbine's mechanical power: Adopting about The original mechanical power characteristics are characterized by a quadratic function in one variable, and the equivalent mechanical power of the wind turbine is obtained: (6); In the formula, ρ air density; R The radius of the wind turbine; v w Wind speed; N This refers to the gearbox transmission ratio; This refers to the mechanical angular velocity of the fan rotor. c 0 represents the quadratic fitting coefficient of the equivalent wind energy utilization coefficient; For equivalent mechanical power, It is the equivalent wind energy utilization coefficient. c 1- c 3 is a constant coefficient; equivalent mechanical power Replacement of original mechanical power At that time, the following conditions must be met: (1) Only wind turbines operating in the wind speed range of 7 m / s to 11 m / s participate in frequency regulation. At this time, the wind turbines are running in MPPT mode, and the pitch angle is [missing information]. Keep it at 0, equivalent mechanical power The pitch angle variable is no longer involved; (2) Frequency regulation is only carried out by releasing rotor kinetic energy, without using load reduction operation or variable pitch angle power reserve mode; Simplify the electromechanical dynamics of the wind turbine: To simplify the modeling process, ignore Higher-order terms, only retain The first term; utilizing equivalent mechanical power Replacement of original mechanical power Equation (4) can be reformulated as follows: (7); In the formula, This is a linearization of the second term on the right-hand side of equation (4), i.e., the MPPT control output power command. ; This is a linearization of the third term on the right-hand side of equation (4), i.e., equivalent mechanical power. ,coefficient and , and The expression is shown below; (8); (9); Rearranging terms in equation (6), we get and Explicit relationships between them: (10); Establish the relationship between frequency response power and the change in rotor mechanical angular velocity: Simultaneous equations and equivalent mechanical power The result of linearization is used to establish the frequency response power. With the change in rotor mechanical angular velocity Relationship: (11); In the formula, To represent the frequency response power in the complex frequency domain, in equation (9) Substituting into equation (10), we obtain the frequency response power. With frequency change Relationship: (12).

[0032] Furthermore, frequency response performance analysis based on the system frequency analytical model includes: The system frequency analytical model is compared with the traditional simplified model that ignores the internal electromechanical coupling dynamics of the wind turbine to determine the deviation between the system frequency minimum point and the frequency recovery rate. By comparing the wind turbine response power corresponding to the system frequency analytical model and the traditional simplified model, the active power output attenuation characteristics and reverse power absorption characteristics during the frequency regulation process are determined. The analytical model of the system frequency is compared with the refined simulation model to determine the model errors of the frequency drop rate, the system frequency minimum point, and the frequency recovery trajectory.

[0033] Furthermore, based on the system frequency analytical model, the frequency modulation control parameters are configured collaboratively, including: By changing the virtual inertia control parameters, the effects of the virtual inertia control parameters on the initial frequency change rate of the disturbance, the lowest point of the system frequency, and the frequency recovery overshoot were determined. By changing the droop control parameters, the effects of the droop control parameters on the frequency descent rate, the system frequency minimum point, and the frequency recovery overshoot were determined. Based on the influence of virtual inertia control parameters and droop control parameters, and combined with the releaseable rotor kinetic energy and rotor speed safety constraints of the wind turbine, frequency regulation control parameters are determined.

[0034] As a preferred embodiment of the above, a system frequency analytical model is established and performance analysis is performed: By performing a common denominator simplification, the change in system frequency is obtained. Complex frequency domain expression: (13); In the formula, a 2. a 1 and a 0 represents the numerator polynomial coefficient of the complex frequency domain expression for the system frequency change; b 4. b 3. b 2 and b 1 represents the denominator polynomial coefficients of the complex frequency domain expression for the system frequency change. Each polynomial coefficient is determined by the system inertia, load damping, synchronous generator parameters, wind turbine parameters, and frequency regulation control parameters. Based on the above equation, the mathematical analytical model of the system frequency is obtained: (14); In the formula, F (s) is the frequency response transfer function between the wind turbine response power and the system frequency change; k fd This refers to the virtual inertia control coefficient. k fp This is the droop control coefficient; H dfig The equivalent inertia time constant of the doubly fed wind turbine; ω 0 represents the initial rotor mechanical angular velocity of the wind turbine before it participates in frequency regulation; C 1 represents the linearization coefficient of the maximum power point tracking control output power at the initial operating point; A is the linearization coefficient of the equivalent mechanical power at the initial operating point; based on equation (13), a frequency analysis model of the wind power grid-connected system considering the frequency regulation dynamics of the wind turbine is obtained, and used to analyze the influence of the wind turbine operating state and control parameters on the system frequency response. In the offshore multi-grid-connected receiving-end wind power system oriented towards fast frequency and voltage response, the system frequency analysis model is used to characterize the electromechanical dynamic process of the wind turbine participating in frequency regulation by releasing rotor kinetic energy, and serves as the basis for the frequency response model of system electromechanical dynamic analysis modeling and performance analysis. The overall modeling and analysis method flowchart is as follows: Figure 4 As shown.

[0035] Example 2; Based on the same inventive concept as the offshore wind turbine-electric coupling frequency response analysis method in the foregoing embodiments, the present invention also provides an offshore wind turbine-electric coupling frequency response analysis system, the system comprising: The operating parameter acquisition module acquires the operating parameters of offshore multi-grid-connected receiving-end wind power systems. The frequency response construction module establishes a system frequency response relationship based on operating parameters to characterize the system frequency change under power disturbances. An electromechanical coupling equivalent module is used to establish the electromechanical coupling relationship between the system frequency change, rotor motion state quantity and wind turbine response power, and a nonlinear parameterized equivalent model of wind turbine mechanical power is constructed based on the rotor motion state quantity. The wind power response analysis module linearizes the electromechanical coupling relationship based on a nonlinear parameterized equivalent model and eliminates rotor motion state variables to obtain the wind power response analysis relationship between the wind turbine response power and the system frequency change. The system frequency analysis module substitutes the wind power response analysis relationship into the system frequency response relationship to obtain a system frequency analysis model that takes into account the internal electromechanical coupling dynamics of the wind turbine.

[0036] The system described above in this invention can effectively implement an analytical method for the electrical coupling frequency response of offshore wind turbines, and the technical effects it can achieve are as described in the above embodiments, and will not be repeated here.

[0037] Example 3; Based on the same inventive concept as the offshore wind turbine electrical coupling frequency response analysis method in the foregoing embodiments, the present invention also provides a computer-readable storage medium storing a computer program, the computer program including program instructions, which, when executed by a processor, can realize the offshore wind turbine electrical coupling frequency response analysis method.

[0038] Example 4; To verify the effectiveness of the electromechanical dynamic analytical modeling and performance analysis method for offshore multi-grid-connected receiving-end wind power systems with fast frequency and voltage response, a frequency response simulation model of the offshore wind power grid-connected system was built on the MATLAB / Simulink platform. The simulation model was used to verify the electromechanical dynamic characteristics of the wind turbines participating in the fast frequency response process and to analyze the impact of frequency regulation control parameters on the system's frequency response performance. In the simulation, the initial wind speed of the wind turbines was set to 11 m / s, and the system experienced an active power disturbance at 50 s; the virtual inertia coefficient... k d Take 5, the maximum speed reduction coefficient k max The value is set to 0.3, meaning the minimum permissible speed is the initial speed. ω 0.7 times 0; droop coefficient k p The values ​​were 5, 10, 15, and 20, respectively. All other system and unit parameters used the same baseline values ​​to ensure comparability of the results across groups.

[0039] 1) Verification of frequency support effect

[0040] To verify the effectiveness of the electromechanical dynamic analytical modeling and performance analysis method for offshore multi-grid-connected receiving-end wind power systems with fast frequency and voltage response in frequency support analysis, the detailed frequency response model used in this invention is compared with the traditional frequency response model that does not consider the internal dynamics of the wind turbine. Both models are simulated under the same active power disturbance conditions, and the system frequency response curves are obtained respectively.

[0041] according to Figure 5 and Figure 6 The results shown indicate that in the traditional frequency response model, as the droop coefficient increases... As the frequency increases, the overall system frequency trajectory rises; in the detailed frequency response model, different... The corresponding system frequency trajectories exhibit an intersection phenomenon, and when When the value is large, the system frequency recovery speed decreases. Compared with the detailed frequency response model, the traditional frequency response model overestimates the system frequency minimum. Simulation results show that the traditional frequency response model, which does not take into account the internal dynamics of the wind turbine, cannot accurately characterize the dynamic characteristics of the wind turbine participating in primary frequency regulation. The detailed frequency response model used in this invention takes into account the internal dynamics of the wind turbine, such as speed, maximum power point tracking, and mechanical power changes, and can be used for frequency safety assessment and frequency regulation control parameter tuning of offshore multi-grid-connected receiving-end wind power systems.

[0042] 2) Verification of the dynamic mechanism of active power

[0043] To verify the ability of the electromechanical dynamic analytical modeling and performance analysis method for offshore multi-grid-connected receiving-end wind power systems with fast frequency and voltage response of this invention to characterize the dynamic process of active power of wind turbine generators, the frequency response power of wind turbine generators under the traditional frequency response model and the detailed frequency response model are compared. The results are as follows: Figure 7 and Figure 8 As shown.

[0044] Figure 7 and Figure 8 The results show that in the traditional frequency response model, the frequency response power of the wind turbine remains positive after the disturbance occurs, and increases with the droop coefficient. The frequency response increases with the increase of [unclear - possibly referring to a specific characteristic or factor]. In the detailed frequency response model, the peak power of the wind turbine frequency response is relatively low, then decays earlier, and can drop below zero. This result indicates that in the later stages of frequency regulation, the wind turbine may no longer generate active power and may enter a phase of absorbing active power from the system, thus weakening the support capability of the frequency recovery phase. When [unclear - possibly referring to a specific characteristic or factor] As the frequency increases, the power decrease in the detailed frequency response model becomes more pronounced, a phenomenon corresponding to the simulation results showing a reduction in the system's frequency recovery speed. Therefore, traditional frequency response models alone are insufficient to accurately describe the dynamic changes in active power during the rapid frequency response process of wind turbines. Through the above comparison, the detailed frequency response model employed in this invention can characterize the internal power coupling relationship of wind turbines and can be used for the dynamic mechanism analysis of active power during the rapid frequency response process of offshore multi-grid-connected receiving-end wind power systems.

[0045] 3) Model validity verification

[0046] Figure 9 The results shown indicate that when the sagging coefficient... When the values ​​are 5 and 10, the frequency trajectories obtained from the system frequency mathematical model and the detailed simulation model are basically consistent; when When the values ​​are 15 and 20, the two models maintain good consistency in terms of frequency descent rate and frequency minimum point, with some deviation only occurring during the frequency recovery phase. The deviation mainly stems from the simplification of higher-order speed terms and the approximation of equivalent mechanical power in the low-speed range. Since the system frequency mathematical model can effectively characterize key frequency safety indicators such as the frequency change rate and frequency minimum point, the electromechanical dynamic analytical model established in this invention can be used for frequency response analysis and frequency regulation parameter tuning of wind power grid-connected systems.

[0047] 4) Verification of the influence of frequency modulation parameters

[0048] To verify the analytical capability of the method of this invention in terms of the influence of frequency modulation parameters, the virtual inertia coefficient was further examined. and droop coefficient The impact on the system frequency response. In the simulation, the wind speed was maintained at 11 m / s; the virtual inertia coefficient was analyzed. season and make It varies within the range of 5 to 30; analyze the droop coefficient. season and make It varies within the range of 5 to 30.

[0049] Figure 10 The results shown indicate that increasing the virtual inertia coefficient... It can reduce the rate of frequency change in the initial stage of the disturbance, but has limited improvement on the lowest frequency point; when When the value is too large, the lowest frequency point may be further reduced, and a significant overshoot may occur during the recovery phase. Figure 11 The results shown indicate that increasing the droop coefficient... It can reduce the rate of change in the later stage of frequency descent and raise the minimum frequency point without causing significant overshoot. Therefore, the virtual inertia element is mainly used to improve the rate of change in frequency in the early stage of disturbance, while the droop element is mainly used to improve the dynamic characteristics at the minimum frequency point and in the later stage of frequency descent. In offshore multi-grid-connected receiving-end wind power systems oriented towards rapid frequency and voltage response, the virtual inertia coefficient and droop coefficient need to be coordinated and configured in conjunction with the releaseable kinetic energy of the wind turbine and speed safety constraints.

[0050] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. An analytical method for the electrical coupling frequency response of offshore wind turbines, characterized in that, The method includes: Obtain operating parameters of offshore multi-grid-connected receiving-end wind power systems; Based on the aforementioned operating parameters, a system frequency response relationship is established to characterize the system frequency change under power disturbance. Establish the electromechanical coupling relationship between the system frequency change, rotor motion state quantity and wind turbine response power, and construct a nonlinear parameterized equivalent model of wind turbine mechanical power based on the rotor motion state quantity; The electromechanical coupling relationship is linearized based on the nonlinear parameterized equivalent model, and the rotor motion state quantity is eliminated to obtain the wind power response analytical relationship between the wind turbine response power and the system frequency change. Substituting the wind power response analytical relationship into the system frequency response relationship, a system frequency analytical model considering the electromechanical coupling dynamics within the wind turbine is obtained.

2. The analytical method for the electrical coupling frequency response of offshore wind turbines according to claim 1, characterized in that, The operating parameters include system parameters, synchronous generator parameters, and wind turbine parameters; The system parameters include the power ratio of synchronous generator units, wind power grid connection penetration rate, system equivalent inertia time constant, and load damping coefficient. The system frequency response relationship includes the coupling relationship between the system frequency change, system disturbance power, synchronous generator response power and wind turbine response power; The synchronous unit response power is determined by the synchronous unit frequency response model that retains the reheat dynamic link.

3. The analytical method for the electrical coupling frequency response of offshore wind turbines according to claim 1, characterized in that, The rotor motion state quantity is the change in the mechanical angular velocity of the wind turbine rotor; the nonlinear parameterized equivalent model uses a function with the mechanical angular velocity of the wind turbine rotor as the independent variable to characterize the mechanical power of the wind turbine; the model parameters of the nonlinear parameterized equivalent model are determined based on the wind turbine impeller parameters, gearbox parameters, generator parameters and real-time wind speed.

4. The analytical method for the electrical coupling frequency response of offshore wind turbines according to claim 1, characterized in that, The nonlinear parameterized equivalent model is applicable to wind turbines operating in maximum power point tracking mode and with pitch angle remaining at zero. The wind turbine provides the wind turbine response power by releasing rotor kinetic energy, and does not adopt load reduction operation mode or pitch reserve mode.

5. The analytical method for the electrical coupling frequency response of offshore wind turbines according to claim 1, characterized in that, The electromechanical coupling relationship couples maximum power point tracking control, virtual inertia control, and droop control; the linearization process includes ignoring higher-order terms of the rotor motion state variables and linearizing the output power of maximum power point tracking control and the equivalent mechanical power determined by the nonlinear parameterized equivalent model, respectively.

6. The analytical method for the electrical coupling frequency response of offshore wind turbines according to claim 1, characterized in that, Obtain the analytical relationship of wind power response, including: Based on the electromechanical coupling relationship after linearization, a first analytical relationship is determined between the rotor motion state quantity and the system frequency change quantity. Based on the rotor kinetic energy release process, a second analytical relationship is determined between the wind turbine response power and the rotor motion state quantity; Substitute the first analytical relation into the second analytical relation and eliminate the rotor motion state quantity to obtain the wind power response analytical relation.

7. The analytical method for the electrical coupling frequency response of offshore wind turbines according to claim 1, characterized in that, Frequency response performance analysis based on the system frequency analytical model includes: The system frequency analytical model is compared with the traditional simplified model that ignores the internal electromechanical coupling dynamics of the wind turbine to determine the deviation between the system frequency minimum point and the frequency recovery rate. By comparing the wind turbine response power corresponding to the system frequency analytical model and the traditional simplified model, the active power output attenuation characteristics and reverse power absorption characteristics during the frequency regulation process are determined. The system frequency analytical model is compared with the refined simulation model to determine the model errors of the frequency drop rate, the system frequency minimum point, and the frequency recovery trajectory.

8. The analytical method for the electrical coupling frequency response of offshore wind turbines according to claim 1, characterized in that, Based on the system frequency analytical model, the frequency modulation control parameters are configured collaboratively, including: By changing the virtual inertia control parameters, the effects of the virtual inertia control parameters on the initial frequency change rate of the disturbance, the lowest point of the system frequency, and the frequency recovery overshoot were determined. By changing the droop control parameters, the effects of the droop control parameters on the frequency descent rate, the system frequency minimum point, and the frequency recovery overshoot are determined. Based on the influence of the virtual inertia control parameters and the droop control parameters, and in conjunction with the releaseable rotor kinetic energy and rotor speed safety constraints of the wind turbine, the frequency regulation control parameters are determined.

9. A frequency response analysis system for offshore wind turbine coupling, characterized in that, The system includes: The operating parameter acquisition module acquires the operating parameters of offshore multi-grid-connected receiving-end wind power systems. The frequency response construction module establishes a system frequency response relationship based on operating parameters to characterize the system frequency change under power disturbances. An electromechanical coupling equivalent module is used to establish the electromechanical coupling relationship between the system frequency change, rotor motion state quantity and wind turbine response power, and a nonlinear parameterized equivalent model of wind turbine mechanical power is constructed based on the rotor motion state quantity. The wind power response analysis module linearizes the electromechanical coupling relationship based on a nonlinear parameterized equivalent model and eliminates rotor motion state variables to obtain the wind power response analysis relationship between the wind turbine response power and the system frequency change. The system frequency analysis module substitutes the wind power response analysis relationship into the system frequency response relationship to obtain a system frequency analysis model that takes into account the internal electromechanical coupling dynamics of the wind turbine.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which includes program instructions that, when executed by a processor, can implement the offshore wind turbine electro-coupled frequency response analysis method as described in any one of claims 1-8.

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