Method and system for uniform suppression of wide-band oscillations in offshore wind power flexible direct grid connection system

Abstract

The application discloses a wideband oscillation uniform suppression method and system of an offshore wind power flexible direct current grid-connected system, relates to the technical field of offshore wind power flexible direct current grid-connected control, and comprises the following steps: performing multi-source signal decoupling and frequency domain joint mapping on wideband oscillation characteristic parameters to generate real-time signal characteristic data; processing the real-time signal characteristic data through impedance cooperative tuning and energy transmission path reconstruction to generate port energy absorption parameters; performing asymmetric coupling attenuation and time domain sequence reorganization on the port energy absorption parameters to generate post-port dissipation electrical state parameters; processing the post-port dissipation electrical state parameters through switch sequence cooperative application to generate source end spectrum optimization parameters; and after performing feature analysis and classification on the global parameters, constructing the real-time signal characteristic data by adopting independent component analysis and frequency domain joint mapping, which not only enhances the decoupling and unity of the multi-source signals, but also provides accurate basis for subsequent regulation and control.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of offshore wind power flexible direct current grid connection control technology, in particular to a method and system for uniform suppression of wideband oscillation of offshore wind power flexible direct current grid connection system. BACKGROUND

[0002] With the large-scale development of global renewable energy, offshore wind power as an important clean energy form, its flexible direct current (VSC-HVDC) grid connection technology has been widely used. The flexible direct current grid connection system has significant advantages in long-distance offshore wind power grid connection, tidal and wind speed fluctuation adaptability, and system stability due to its flexible power transmission capacity and fast regulation characteristics. In recent years, related researches mainly focus on the dynamic characteristic analysis, control strategy optimization and oscillation suppression technology development of the flexible direct current grid connection system. For example, by improving the local damping adjustment of the controller, using virtual inertia and multi-port resonant control, etc., the influence of system low-frequency and local oscillation can be alleviated to a certain extent.

[0003] The prior art still has optimization space in uniform suppression of wideband oscillation. Specifically, the traditional method usually relies on a single control strategy or local damping adjustment when dealing with multi-port, multi-source signal interaction and wideband oscillation energy distribution, which is difficult to realize global collaborative energy dispersion and frequency spectrum optimization. This may to some extent lead to the concentration of oscillation energy in some ports or time domain response imbalance, thereby limiting the overall dynamic stability and power regulation flexibility of the system. SUMMARY

[0004] In view of the above existing problems, the present application is proposed.

[0005] Therefore, the present application provides a method for uniform suppression of wideband oscillation of offshore wind power flexible direct current grid connection system to solve the problems of uneven distribution of oscillation energy and insufficient frequency spectrum optimization.

[0006] To solve the above technical problems, the present application provides the following technical solutions:

[0007] In a first aspect, the present application provides a method for uniform suppression of wideband oscillation of offshore wind power flexible direct current grid connection system, which comprises collecting wind power flexible direct current grid connection global parameters and performing feature analysis and time domain classification processing to generate wideband oscillation characteristic parameters;

[0008] The wideband oscillation characteristic parameters are subjected to multi-source signal decoupling and frequency domain joint mapping to generate real-time signal feature data;

[0009] The real-time signal feature data is subjected to impedance collaborative tuning and energy transmission path reconstruction processing to generate port energy absorption parameters;

[0010] The port energy absorption parameters are asymmetrically coupled and attenuated, and time domain sequence is reorganized to generate the electrical state parameters after port dissipation;

[0011] The electrical state parameters after port dissipation are processed through switch sequence cooperation to generate source end spectrum optimization parameters;

[0012] The source end spectrum optimization parameters are subjected to power control and safety protection processing to generate oscillation suppression results.

[0013] As a preferred scheme of the offshore wind power flexible direct current grid-connected system wideband oscillation uniform suppression method, the wideband oscillation characteristic parameters are generated by the following specific steps,

[0014] The wind power flexible direct current grid-connected global parameters are subjected to data synchronization, denoising filtering and standardization processing to obtain unified global parameters;

[0015] The unified global parameters are subjected to signal decomposition and frequency energy analysis to obtain frequency band oscillation energy distribution data;

[0016] The multi-dimensional decomposition calculation is performed on the frequency band oscillation energy distribution data, the instantaneous voltage, current, power and phase characteristics are extracted, and the nonlinear integration and frequency-time domain coupling mapping processing are performed to generate the wideband oscillation characteristic parameters.

[0017] As a preferred scheme of the offshore wind power flexible direct current grid-connected system wideband oscillation uniform suppression method, the real-time signal characteristic data are generated by the following specific steps,

[0018] The wideband oscillation characteristic parameters are decoupled by independent component analysis to generate decoupled oscillation characteristic data;

[0019] The decoupled oscillation characteristic data are subjected to frequency domain joint mapping and feature integration to generate real-time signal characteristic data.

[0020] As a preferred scheme of the offshore wind power flexible direct current grid-connected system wideband oscillation uniform suppression method, the real-time signal characteristic data are generated by the following specific steps,

[0021] The instantaneous amplitude, phase and frequency characteristics of each port are extracted from the decoupled oscillation characteristic data, and unified scale standardization processing is performed to generate normalized frequency domain feature vectors;

[0022] The normalized frequency domain feature vectors are jointly processed by port coupling mapping and frequency interaction calculation to generate port frequency domain interaction features;

[0023] The port frequency domain interaction features are integrated and subjected to nonlinear normalization processing to generate real-time signal characteristic data.

[0024] As a preferred scheme of the offshore wind power flexible direct current grid-connected system wide-band oscillation uniform suppression method, the port energy absorption parameters are generated, and the specific steps are as follows,

[0025] The port impedance is cooperatively tuned according to the real-time signal characteristic data, and the optimal port impedance parameters are obtained.

[0026] The optimal port impedance parameters are combined with the electrical characteristics of each port and the transmission characteristics of the submarine cable to reconstruct the energy flow and optimize the transmission path, and the port oscillation energy distribution is generated.

[0027] The port oscillation energy distribution is analyzed by energy partition, impedance adjustment and phase frequency coupling calculation, and the port energy absorption parameters are generated.

[0028] As a preferred scheme of the offshore wind power flexible direct current grid-connected system wide-band oscillation uniform suppression method, the port energy absorption parameters are generated, and the specific steps are as follows,

[0029] The instantaneous amplitude of each port is extracted from the port oscillation energy distribution and processed by nonlinear mapping to generate amplitude adjustment information, and the nonlinear cooperative adjustment of port impedance coupling is performed to generate impedance adjustment information.

[0030] The impedance adjustment information is calculated by nonlinear phase and frequency to generate coupling correction information.

[0031] The amplitude adjustment information, impedance adjustment information and coupling correction information are combined to generate the port energy absorption parameters.

[0032] As a preferred scheme of the offshore wind power flexible direct current grid-connected system wide-band oscillation uniform suppression method, the port energy absorption parameters are generated, and the specific steps are as follows,

[0033] The port attenuation characteristic values are generated by differentiating and attenuating the port energy absorption parameters according to the oscillation coupling strength between the ports.

[0034] The port attenuation characteristic values are integrated by sliding window and processed by time domain normalization to generate the post-dissipation electrical state parameters of the port.

[0035] As a preferred scheme of the offshore wind power flexible direct current grid-connected system wide-band oscillation uniform suppression method, the source end frequency spectrum optimization parameters are generated, and the specific steps are as follows,

[0036] The post-dissipation electrical state parameters of the port are cooperatively matched with the switching sequence to obtain a cooperative switching control sequence, and the frequency spectrum is mapped to generate a source end frequency distribution characteristic matrix.

[0037] Energy normalization and segmented mapping are performed on the source-end frequency distribution feature matrix to generate an optimized feature set of the source-end frequency band;

[0038] Nonlinear fusion and coordinated adjustment processing is performed on the source-end frequency band optimization feature set to generate source-end spectrum optimization parameters.

[0039] As a preferred embodiment of the broadband oscillation uniformity suppression method for the offshore wind power flexible DC grid-connected system described in this invention, the specific steps for generating the oscillation suppression result are as follows:

[0040] Power peak limiting and high-power band suppression are applied to the source-end spectrum optimization parameters to generate a controlled power reference, and nonlinear power adjustment is performed to obtain the power distribution vector;

[0041] The power distribution vector is modified by safety constraints to generate a safety protection vector, and a composite power coupling operation is performed to obtain the oscillation suppression result.

[0042] Secondly, the present invention provides a broadband oscillation uniformity suppression system for offshore wind power flexible DC grid connection system, including a parameter acquisition module for acquiring global parameters of wind power flexible DC grid connection, and performing feature analysis and time-domain classification processing to generate broadband oscillation characteristic parameters.

[0043] The signal decoupling module is used to decouple multi-source signals and perform frequency domain joint mapping on broadband oscillation characteristic parameters to generate real-time signal feature data.

[0044] Impedance tuning module is used to process real-time signal characteristic data through impedance co-tuning and energy transmission path reconstruction to generate port energy absorption parameters.

[0045] The attenuation and reshaping module is used to perform asymmetric coupling attenuation and time-domain sequence reshaping on the port energy absorption parameters to generate the electrical state parameters after port dissipation.

[0046] The switch application module is used to process the electrical state parameters after port dissipation through a switch sequence to generate source-side spectrum optimization parameters.

[0047] The power control and protection module is used to perform power control and safety protection processing on the source-end spectrum optimization parameters and generate oscillation suppression results.

[0048] The beneficial effects of this invention are as follows: After performing feature analysis and classification on the parameters across the entire domain, independent component analysis and frequency domain joint mapping are used to construct real-time signal feature data, which not only enhances the decoupling and unification of multi-source signals, but also provides a precise basis for subsequent regulation; furthermore, by combining impedance coordinated tuning with port characteristics and transmission characteristics to reconstruct energy flow, and supplemented by nonlinear adjustment to generate port energy absorption parameters, energy sharing and dynamic absorption between ports are realized, forming a uniform and coordinated oscillation suppression mechanism across the entire link range, effectively improving the stability and reliability of offshore wind power flexible DC grid connection. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Fig. 1 A flowchart for a broadband oscillation uniformity suppression method for offshore wind power flexible DC grid-connected systems.

[0051] Fig. 2 This is a schematic diagram of a broadband oscillation uniformity suppression system for a flexible DC grid-connected offshore wind power system.

[0052] Fig. 3 This is a flowchart of a broadband oscillation uniformity suppression method.

[0053] Fig. 4 A detailed flowchart is generated for the port energy absorption parameters. Detailed Implementation

[0054] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0055] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0056] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0057] Reference Figs. 1-4As one embodiment of the present invention, this embodiment provides a method for uniformly suppressing broadband oscillations in an offshore wind power flexible DC grid-connected system, comprising the following steps:

[0058] S1. Collect parameters of the entire domain of wind power flexible DC grid connection, and perform feature analysis and time-domain classification processing to generate broadband oscillation characteristic parameters.

[0059] It should be noted that the full range of parameters for wind power flexible DC grid connection includes turbine output, current and voltage, converter station port current and voltage, electrical transmission characteristics of submarine cables and buses, DC bus topology information and converter switching status.

[0060] S1.1 Perform data synchronization, noise reduction filtering, and standardization on the parameters of the entire wind power flexible DC grid connection to obtain unified parameters across the entire region.

[0061] Furthermore, raw parameters such as current, voltage, topology, and switch status are simultaneously collected from multiple components including wind turbine units, converter station ports, submarine cables, and busbars. The collected data undergoes unified time-base processing to ensure the timing consistency of signals from different sources. Random interference and measurement errors are then removed through filtering and noise elimination methods. The processed signals are normalized and structured in terms of amplitude, phase, and frequency to obtain unified global parameters.

[0062] S1.2 Perform signal decomposition and frequency energy analysis on the unified global parameters to obtain oscillation energy distribution data for each frequency band.

[0063] Furthermore, the signal components in the unified global parameters are classified and identified. Based on the differences in the response characteristics of current, voltage, and power signals in the sampled waveforms, corresponding time series data are extracted respectively. During the decomposition process, the data streams of different signal channels are independently separated according to the source channel and physical properties of the measured signal. For example, voltage channel data is extracted into voltage time series, current channel data into current time series, and power channel data into power time series, thereby achieving channel decomposition of the unified global parameters. The extracted time-domain waveforms are processed by feature filtering and noise suppression to obtain the independent feature components of each channel. Based on the fast Fourier transform or multi-resolution time-frequency decomposition method, the decomposed signal is mapped to the frequency domain space, and the amplitude and phase information of each frequency point are extracted. Through energy calculation and frequency band aggregation, the energy in different frequency ranges is statistically analyzed and classified to obtain the oscillation energy distribution of each frequency band.

[0064] S1.3 Perform multidimensional decomposition calculations on the oscillation energy distribution data of each frequency band, extract instantaneous voltage, current, power and phase characteristics, and perform nonlinear integration and frequency-time domain coupling mapping processing to generate broadband oscillation characteristic parameters.

[0065] Furthermore, by using Fourier transform or wavelet transform, the signal of each frequency band is separated in the time and frequency domains, and instantaneous voltage, instantaneous current, instantaneous power, and phase features are extracted. The extracted instantaneous voltage, instantaneous current, instantaneous power, and phase features are then nonlinearly integrated through amplitude squared, phase coupling, or power normalization. Simultaneously, the integrated instantaneous voltage, instantaneous current, instantaneous power, and phase features are subjected to frequency-time domain coupling mapping to establish a correspondence between different frequency bands and time domain windows. Based on the energy concentration, phase continuity, and amplitude variation trend of the signal, the matching relationship between the features of each frequency band and the time interval is determined, thereby realizing the synchronous correlation and coupling fusion of time domain features and frequency domain features. The time domain features and frequency domain features are fused to generate broadband oscillation characteristic parameters that can reflect broadband oscillation characteristics and maintain time-frequency correlation.

[0066] S2. Decouple and jointly map the wideband oscillation characteristic parameters from multiple sources to generate real-time signal characteristic data.

[0067] S2.1 Decouple the broadband oscillation characteristic parameters through independent component analysis to generate decoupled oscillation characteristic data.

[0068] Furthermore, the broadband oscillation characteristic parameters are organized into a two-dimensional matrix according to the time series. Each column represents the complete feature vector of voltage, current, power, and phase at a time point, and each row represents the change of each dimension feature over the entire time series. The dimensional differences are eliminated by mean removal and covariance standardization. Independent component analysis is applied to the standardized two-dimensional matrix. By assuming that the source signals are independent of each other, the two-dimensional matrix is ​​decomposed into several statistically independent components. Each component is linearly reconstructed. Based on the mixing matrix and separation matrix parameters obtained from the independent component analysis, the independent components are recombined in the original feature space according to the linear superposition relationship to restore the corresponding components in the feature dimensions such as voltage, current, power, and phase, so as to remove the coupling effect between different source signals and obtain decoupled oscillation characteristic data.

[0069] S2.2 Extract the instantaneous amplitude, phase and frequency features of each port from the decoupled oscillation feature data, perform unified scale standardization processing, and generate normalized frequency domain feature vectors.

[0070] Furthermore, instantaneous amplitude, phase, and frequency features are extracted port by port from the decoupled oscillation characteristic data to form a complete frequency domain feature set for each port at the current time point. The features of different ports and different types (such as voltage features, current features, power features, and phase features) are processed with a unified scale, including amplitude normalization, phase mapping to a unified angle range, and frequency feature standardization, to eliminate differences in dimensions and amplitude. The processed port features are then integrated into a normalized frequency domain feature vector according to the time series.

[0071] S2.3. The normalized frequency domain feature vector is jointly processed through port coupling mapping and frequency interaction calculation to generate inter-port frequency domain interaction features.

[0072] Furthermore, the normalized frequency domain feature vectors are arranged by port index to form a port feature matrix; based on the physical coupling relationship between ports (such as electrical connection, impedance coupling, and transmission path), the features of each port are mapped to the relevant port features to establish a coupling relationship matrix between ports; interactive calculations are performed in the frequency dimension, considering the mutual influence and coupling between different frequency components, and the amplitude, phase, and frequency information are integrated through nonlinear functions or matrix operations to generate frequency domain interactive features between ports.

[0073] S2.4 Integrate and nonlinearly normalize the port frequency domain interaction characteristics to generate real-time signal characteristic data.

[0074] Furthermore, the frequency domain interaction features between ports are summarized according to port and frequency dimensions to form a global feature matrix for the ports. The amplitude, phase and frequency information in the matrix are nonlinearly normalized to map the features of different ports and frequencies to a unified scale, eliminating the influence of dimensional differences and extreme values. During the normalization process, the response of important features is enhanced by a nonlinear function, while suppressing abnormal fluctuations, thus achieving feature smoothing and enhancement. Real-time signal feature data is obtained.

[0075] It should also be noted that key features refer to critical parameters that significantly affect oscillation characteristics and energy transfer during inter-port frequency domain interaction. These mainly include characteristic components with large amplitude variations, significant phase shifts, or prominent frequency fluctuations. These characteristic components typically reflect the main sources of change in inter-port energy coupling strength, oscillation stability, and power transfer efficiency. They are amplified during normalization and nonlinear enhancement processes to highlight their dominant role in the overall oscillation behavior.

[0076] S3. Real-time signal characteristic data is processed through impedance co-tuning and energy transmission path reconstruction to generate port energy absorption parameters.

[0077] Existing methods typically process real-time signal characteristic data through single-port impedance matching or local damping control, focusing on the energy absorption efficiency of a single port and reducing local oscillations by adjusting port impedance or damping parameters. However, in cases of multi-port coupling and complex energy transmission paths, it is difficult to achieve global collaborative optimization, and the energy distribution of oscillations between ports cannot be precisely controlled, resulting in limitations in energy absorption.

[0078] This invention processes real-time signal characteristic data through port impedance collaborative tuning and energy transmission path reconstruction. The instantaneous amplitude, phase and frequency characteristics of each port gradually tend to the global optimal state under iterative adjustment. At the same time, the oscillation energy is reconstructed by combining the impedance coupling between ports and the energy transmission path to generate port energy absorption parameters, thereby realizing multi-port collaborative energy absorption and global oscillation suppression, and accurately controlling the energy distribution between ports.

[0079] S3.1 Perform port impedance co-tuning on real-time signal characteristic data to obtain optimal port impedance parameters.

[0080] Furthermore, the real-time signal characteristic data is organized into a port characteristic matrix according to port order. Each row represents the instantaneous amplitude, phase, and frequency characteristics of a single port at different frequencies, and each column represents the instantaneous characteristics of different ports at the same frequency. The port characteristic matrix undergoes coordinated tuning processing, including impedance matching adjustment of the instantaneous amplitude of the ports. The phase correction amount for each port is calculated through impedance coupling relationships, expressed as:

[0081] ;

[0082] in, This indicates the phase correction amount for each port. This indicates the instantaneous amplitude of the current port. Indicates the instantaneous amplitude of adjacent ports. Indicates the port's own resistance. This indicates the coupling resistance between the port and the adjacent port. This represents the coupling reactance between the port and its adjacent ports. This indicates that the amplitude difference and impedance effect are converted into a phase adjustment amount;

[0083] The impedance interaction between ports is iteratively adjusted by combining frequency characteristics; during the iteration process, the port amplitude and phase characteristics are continuously updated to make the port impedance parameters tend to the global optimal state, thus obtaining the optimal port impedance parameters.

[0084] S3.2. Combine the optimal port impedance parameters with the electrical characteristics of each port and the transmission characteristics of the submarine cable to reconstruct the energy flow and optimize the transmission path, thereby generating the port oscillation energy distribution.

[0085] Furthermore, the optimal port impedance parameters are correlated with the electrical characteristics of each port and the transmission characteristics of the submarine cable according to the port correspondence. The voltage, current, power, and phase characteristics of each port are combined with the transmission characteristics of the submarine cable, such as resistance, reactance, and transmission delay. During the energy flow reconstruction process, the instantaneous energy flow direction and distribution of each port are calculated based on the impedance and electrical connection relationship between the ports. The optimal path is determined based on conditions such as minimum energy transmission loss, maximum impedance matching degree, and minimum phase difference. By comparing the energy attenuation rate and power stability under different paths, the path with the most balanced energy transfer and the minimum loss is selected as the optimal path, so that the energy is distributed along the optimal path, and the oscillating energy between the ports is uniformly transferred. During the transmission path optimization process, the energy flow path and impedance matching between the ports are continuously corrected according to the characteristics of each port and the submarine cable to ensure that the energy flow is evenly distributed at different frequencies, generating the port oscillation energy distribution.

[0086] It should also be noted that the electrical characteristics of each port are obtained by collecting the port current, voltage, power and port topology information of the converter station; the transmission characteristics of the submarine cable are obtained by collecting parameters such as the length, cross-section, resistance, reactance and electromagnetic transmission delay of the submarine cable.

[0087] The electrical characteristics of each port refer to the dynamic attributes such as voltage, current, power, phase, and impedance exhibited by each port during energy transmission and oscillation. These attributes reflect the port's response characteristics to energy flow at different frequencies. High-precision sensors are used to acquire real-time electrical signals from the ports. Time-frequency analysis and parameter identification are used to calculate the electrical response values ​​of the ports at each frequency band. These values ​​are then fitted and corrected using historical operating data to obtain the port electrical characteristic parameters used for energy flow reconstruction.

[0088] Submarine cable transmission characteristics refer to the frequency-related parameters exhibited by the submarine cable during energy transmission between ports, such as resistance, reactance, capacitance, transmission delay, and attenuation rate. These parameters determine the transmission efficiency and phase changes of energy at different frequencies. A transmission model is established based on the structural parameters of the submarine cable (such as length, cross-section, and dielectric properties). Combined with measured frequency response data and simulation calculations, the submarine cable transmission characteristic parameters at various frequency bands are obtained.

[0089] Port correspondence refers to the interrelationship of ports in the electrical connection network and the corresponding energy transmission path. Based on the topology of wind power flexible DC grid connection and port connection characteristics, the direction and interaction of energy transmission are determined by identifying the voltage, current and phase difference between ports, forming a port correspondence mapping for energy flow reconfiguration.

[0090] S3.3 Extract the instantaneous amplitude of each port from the port oscillation energy distribution and perform nonlinear mapping processing to generate amplitude adjustment information, and perform nonlinear coordinated adjustment of port impedance coupling to generate impedance adjustment information.

[0091] Furthermore, the instantaneous amplitude characteristics of the port oscillation energy distribution are extracted one by one according to the port sequence. The instantaneous amplitude characteristics are mapped to a specified response range (such as the rated power response range, voltage safety range, or allowable oscillation amplitude range) through a nonlinear mapping method to generate amplitude adjustment information. Based on the impedance relationship between the ports, the amplitude adjustment information is used as input for nonlinear coordinated adjustment to adjust the amplitude and phase response of the port impedance, so that each port achieves a coordinated matching state during the oscillation energy transfer process, thereby generating impedance adjustment information.

[0092] It should also be noted that the impedance relationship between ports refers to the impedance interaction characteristics formed between different ports in the electrical connection, reflecting the degree of coupling of voltage, current, and phase in the energy transfer process. This relationship is calculated by measuring the impedance amplitude and phase characteristics of each port at different frequencies, combined with the transmission parameters of the submarine cable (such as reactance, resistance, and transmission delay), and is used to describe the impedance matching and energy coupling strength in the energy transfer path between ports.

[0093] S3.4 Perform nonlinear phase and frequency composite calculations on the impedance adjustment information to generate coupling correction information.

[0094] Furthermore, the impedance adjustment information is organized according to the port order, and the amplitude, phase, and frequency characteristics of each port are extracted separately. Through nonlinear phase and frequency composite calculation, the amplitude and phase characteristics are coupled in the frequency dimension, taking into account the coupling relationship between the impedance interaction between ports and the oscillation characteristics. During the calculation process, the amplitude and phase response are adjusted iteratively to achieve coordination of the coupling effect between ports. Coupled correction information that can reflect the correction effect of port impedance interaction and oscillation energy transmission is generated.

[0095] It should also be noted that "coupling the amplitude and phase characteristics in the frequency dimension through nonlinear phase and frequency composite calculation" refers to extracting the rate of change of phase with frequency and the trend of change of amplitude with frequency from the amplitude and phase data of each port, and using nonlinear functions (such as power functions or exponential mappings) to process the two together, so that the rate of change of phase has a corrective effect on the frequency offset, while the trend of change of amplitude has a feedback effect on the phase change; by repeatedly calculating this mutual influence relationship at each frequency point, the coordinated change law of amplitude and phase in the frequency dimension can be obtained, which is used to describe the response coupling relationship of the port at different frequencies.

[0096] The "nonlinear phase and frequency composite calculation" employs a frequency-layered algorithm based on nonlinear mapping and recursive correction. Specifically, at each frequency point, the rate of change of phase with frequency and the trend of change of amplitude with frequency are calculated. Nonlinear mapping functions (such as power functions, exponential functions, or tangent mappings) are used to jointly process the changes in amplitude and phase, so that the rate of change of phase affects the correction of frequency offset, while the change in amplitude provides feedback to the change in phase. The frequency range is layered, and each layer recursively corrects the phase adjustment amount of the current layer based on the calculation results of the previous layer, thus obtaining the coordinated change law of amplitude and phase at different frequencies.

[0097] The goal of "iterative adjustment" is to make the phase changes between different frequency layers smooth, the amplitude changes continuous, and to satisfy the balance of energy transfer.

[0098] In each calculation round, the deviation of energy transfer between ports is calculated based on the current amplitude, phase and impedance differences of each port. The amplitude and phase responses of each port are slightly corrected according to the deviation to make the energy flow closer to equilibrium. The result after each correction is substituted into the next round of calculation to update the new deviation. Through multiple rounds of iteration, when the amplitude change and phase shift between two consecutive adjustments tend to be stable, the iteration is considered to have converged and the adjustment process is completed.

[0099] S3.5. Combine the amplitude adjustment information, impedance adjustment information and coupling correction information to generate port energy absorption parameters.

[0100] Furthermore, amplitude adjustment information, impedance adjustment information, and coupling correction information are calculated in combination according to the port order. The amplitude adjustment information of each port is superimposed with the corresponding impedance adjustment information to integrate the instantaneous amplitude and impedance response characteristics of the port. The integrated instantaneous amplitude and impedance response characteristics are then combined with the coupling correction information to consider the impedance interaction, phase response, and frequency coupling relationship between ports, thereby achieving a coordinated distribution of port oscillation energy. Through continuous iterative calculation, the amplitude, impedance, and coupling correction information of each port are brought to a unified equilibrium state, generating the port energy absorption parameters.

[0101] It should also be noted that "the amplitude adjustment information, impedance adjustment information, and coupling correction information are calculated in sequence according to the port number" means that the amplitude adjustment information and impedance adjustment information of each port are paired item by item at the same frequency point according to the port number order. By direct superposition and function mapping, the amplitude change reflects the influence of impedance characteristics. Combined with the coupling correction information, the phase difference and energy coupling between adjacent ports are synchronously corrected, so that the port response reflects the interaction between the local port and the adjacent port in both amplitude and phase. After processing the ports in sequence, composite response data reflecting the interaction and correlation between the amplitude and impedance response characteristics between ports is obtained.

[0102] "Combining the integrated instantaneous amplitude and impedance response characteristics with coupling correction information" refers to: in each port, the integrated instantaneous amplitude and impedance response are expanded point by point according to the frequency change, and the corresponding coupling correction information is introduced. The coupling correction information is used as a modulation factor to describe the phase difference and energy transfer effect between adjacent ports. At each frequency point, the instantaneous amplitude change rate and phase change trend are corrected simultaneously. Through this synchronous correction method, the integrated response characteristics can reflect the coupling strength and frequency correlation between adjacent ports, and establish a dynamic coupling relationship between ports in the frequency dimension.

[0103] "Achieving a unified balance in the amplitude, impedance, and coupling correction information of each port" refers to the process of multi-port calculation. Based on the rate of change of amplitude and impedance phase difference of each port at the current frequency, the direction and magnitude of energy flow between ports are calculated. With the continuity of energy transfer as a constraint, the amplitude response amplitude and impedance phase shift of each port are gradually adjusted to make the energy input and output between adjacent ports tend to be balanced. At the same time, the coupling correction information is used to dynamically compensate for the phase difference between ports to eliminate the energy unevenness caused by frequency coupling. By repeating this balance adjustment process at multiple frequency layers, the coordination and consistency of energy distribution and phase response between ports are achieved, forming an overall balanced state.

[0104] S4. Perform asymmetric coupling attenuation and time-domain sequence renormalization on the port energy absorption parameters to generate the electrical state parameters after port dissipation.

[0105] S4.1. The port energy absorption parameters are differentially attenuated according to the oscillation coupling strength between ports to generate port attenuation characteristic values.

[0106] Furthermore, by comparing the correlation or coupling coefficient between the amplitude, phase, and frequency characteristics of each port and the corresponding characteristics of other ports one by one, the degree of interaction of oscillating energy between ports is quantified. The amplitude, phase, and frequency characteristics of each port are attenuated differently according to their coupling relationship with other ports. The amplitude and phase attenuation of weakly coupled ports are smaller, while the amplitude and phase attenuation of strongly coupled ports are larger. By continuously calculating and adjusting the energy distribution between ports, the balance and coordination of oscillating energy between ports are achieved, and port attenuation characteristic values ​​are generated.

[0107] It should also be noted that corresponding characteristics refer to the amplitude, phase, and frequency characteristics of different ports at the same time point or frequency location, used to compare and quantify the degree of interaction of oscillating energy between ports.

[0108] S4.2 Perform sliding window integration and time-domain normalization on the port attenuation characteristic values ​​to generate electrical state parameters after port dissipation.

[0109] Furthermore, the port attenuation characteristic values ​​are integrated on the time axis in port order using a sliding window. The amplitude, phase, and frequency characteristics of continuous time steps are accumulated or averaged within each sliding window to smooth instantaneous fluctuations and enhance continuity. The integrated port attenuation characteristic values ​​are then normalized in the time domain, mapping the amplitude and phase characteristics to a uniform scale range, eliminating dimensional differences between ports and time steps, ensuring the comparability of oscillation energy at different ports, and generating electrical state parameters after port dissipation.

[0110] S5. The electrical state parameters after port dissipation are processed by the switching sequence to generate source-side spectrum optimization parameters.

[0111] S5.1 Perform switch sequence coordinated matching on the electrical state parameters after port dissipation to obtain the coordinated switch control sequence, and perform spectrum mapping to generate the source end frequency distribution feature matrix.

[0112] Furthermore, the electrical state parameters after port dissipation are processed by switching sequence coordination matching according to the port order. By comparing the instantaneous amplitude, phase, and frequency characteristics of each port with the response characteristics of each switch state of the converter at the same time point, and by calculating the correlation coefficient or Euclidean distance between the port amplitude, phase, and frequency characteristics and the corresponding response characteristics of the switch state, the response strength of each port characteristic to each switch action is evaluated, thereby quantifying the sensitivity of port oscillation energy to different switch actions. Through matching operations, a coordinated switching control sequence that can coordinate port oscillation energy is obtained. The coordinated switching control sequence is mapped in the frequency domain, and combined with the port electrical characteristics and frequency response characteristics, the port oscillation energy under the action of the switching sequence is converted into frequency distribution information, forming a source-end frequency distribution feature matrix.

[0113] It should also be noted that frequency response characteristics refer to the response of a port or converter to changes in the amplitude and phase of an input signal at different frequencies. By applying excitation signals of different frequencies to the port or converter, the amplitude and phase of the output voltage, current, and power as a function of frequency are measured. Alternatively, based on the frequency characteristic parameters provided by the equipment manufacturer, the measurements or parameters are recorded and organized to obtain the amplitude response curve and phase response curve of the port or converter over the entire frequency band, forming the frequency response characteristics used to analyze the oscillation energy transfer and the effect of switching sequences.

[0114] S5.2 Perform energy normalization and segmented mapping on the source-end frequency distribution feature matrix to generate the source-end frequency band optimized feature set.

[0115] Furthermore, the source-end frequency distribution feature matrix undergoes energy normalization in the frequency domain, mapping the amplitude characteristics of each frequency component to a unified scale range, eliminating dimensional differences and amplitude deviations between different frequency bands. The normalized frequency components are then segmented and mapped according to preset frequency band intervals, dividing continuous frequency information into multiple discrete frequency bands. The amplitude and phase characteristics in each discrete frequency band are statistically integrated to generate a source-end frequency band optimized feature set that reflects the oscillation energy distribution characteristics of each frequency band.

[0116] It should also be noted that the process of setting frequency band intervals involves observing and recording the amplitude, phase, and frequency response characteristics of various electrical devices (such as converters, buses, and submarine cables) in wind power flexible DC grid connection, analyzing the oscillation behavior and frequency sensitivity of the devices under different operating conditions, and identifying typical frequency ranges prone to oscillation by combining historical oscillation characteristic parameters; performing spectral statistics on historical oscillation characteristic parameters and source-end frequency distribution characteristic matrix to identify frequency intervals where oscillation energy is concentrated or sensitive, such as low-frequency oscillation regions, subharmonic regions, and high-frequency oscillation regions; and dividing the continuous frequency range into several independent discrete frequency bands covering the entire frequency band by combining the amplitude and phase change characteristics of energy response within each frequency interval, based on the converter switching characteristics, submarine cable transmission characteristics, and bus topology, and presetting these discrete frequency bands as frequency band intervals.

[0117] S5.3 Perform nonlinear fusion and coordinated adjustment processing on the source-end frequency band optimization feature set to generate source-end spectrum optimization parameters.

[0118] Furthermore, by interactively calculating the oscillation energy distribution, phase characteristics, and frequency response within each preset frequency band, the coupling relationship between frequency bands is extracted and normalized and integrated. Then, based on the converter switching characteristics, port electrical characteristics, and submarine cable transmission characteristics, coordinated adjustments are made to adjust the energy distribution and spectral response characteristics of each frequency band, generating source-end spectrum optimization parameters that can reflect the full-band oscillation optimization effect.

[0119] S6. Perform power control and safety protection processing on the source-end spectrum optimization parameters to generate oscillation suppression results.

[0120] S6.1 Perform power peak limitation and high power band suppression on the source-end spectrum optimization parameters to generate a controlled power reference, and perform nonlinear power adjustment to obtain the power distribution vector.

[0121] Furthermore, the impact of oscillation amplitude, phase, and frequency characteristics at different frequency bands on instantaneous power under the influence of port electrical characteristics and submarine cable transmission characteristics is observed and compared. By comparing the amplitude changes, phase shifts, and power responses generated by the oscillation characteristics of each frequency band in the total power output, the dominant role and sensitive position of each frequency band in the total power output are identified, thereby determining the power peak position and high-power range. It is possible to understand the degree of influence of each frequency band on the overall power distribution and adjust the power distribution accordingly to generate a controlled power benchmark. Nonlinear power adjustment is performed on the controlled power benchmark, and frequency band adjustment is carried out based on the spectrum optimization parameters and port oscillation energy distribution to obtain a power distribution vector that reflects the power optimization effect across the entire frequency band.

[0122] S6.2 Perform safety constraint correction on the power distribution vector to generate a safety protection vector, and perform composite power coupling operation to obtain the oscillation suppression result.

[0123] Furthermore, based on the instantaneous amplitude, phase, and power characteristics of each port at different frequencies, combined with the port's electrical characteristics, submarine cable transmission characteristics, and controlled power reference, the real-time power value is compared with the upper and lower limits of the safety boundary. When the power value falls within the boundary range, it is determined to be safe and adjustable; when the power value is close to the boundary, it is determined to be in a critical state, requiring limitation of the adjustment range; when the power value exceeds the boundary, it is determined to be in an out-of-bounds state, requiring forced correction. By comparing the difference between the current power output and the safety boundary, if the power is within the boundary's allowable range, it is marked as adjustable; if the power is close to or exceeds the boundary, it is marked as risky. The adjustment range that needs to be reduced or limited is further calculated to form a safety protection vector. The safety protection vector is then combined with the port oscillation energy distribution and the controlled power reference for composite power coupling calculation. Through inter-band coordinated adjustment and inter-port energy reconstruction, an oscillation suppression result that reflects the full-band oscillation suppression effect is obtained.

[0124] It should also be noted that the adjustable range within the safety boundary refers to the range of adjustment that the port power output can be made within without causing voltage overshoot, frequency instability, equipment overload, or energy imbalance. This range consists of a maximum allowable adjustment value and a minimum allowable adjustment value, and is used to characterize the dynamic adjustment space that the power can make under stable operating conditions, so as to ensure that the oscillation suppression process is both flexible and meets the requirements of electrical stability and equipment safety.

[0125] This embodiment also provides a broadband oscillation uniformity suppression system for offshore wind power flexible DC grid connection system, including: a parameter acquisition module, used to acquire parameters of the entire domain of wind power flexible DC grid connection, and perform feature analysis and time domain classification processing to generate broadband oscillation characteristic parameters;

[0126] The signal decoupling module is used to decouple multi-source signals and perform frequency domain joint mapping on broadband oscillation characteristic parameters to generate real-time signal feature data.

[0127] Impedance tuning module is used to process real-time signal characteristic data through impedance co-tuning and energy transmission path reconstruction to generate port energy absorption parameters.

[0128] The attenuation and reshaping module is used to perform asymmetric coupling attenuation and time-domain sequence reshaping on the port energy absorption parameters to generate the electrical state parameters after port dissipation.

[0129] The switch application module is used to process the electrical state parameters after port dissipation through a switch sequence to generate source-side spectrum optimization parameters.

[0130] The power control and protection module is used to perform power control and safety protection processing on the source-end spectrum optimization parameters and generate oscillation suppression results.

[0131] This embodiment also provides a computer device applicable to the broadband oscillation uniform suppression method for offshore wind power flexible DC grid-connected systems, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the broadband oscillation uniform suppression method for offshore wind power flexible DC grid-connected systems as proposed in the above embodiment.

[0132] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0133] This embodiment also provides a storage medium storing a computer program. When executed by a processor, the program implements the broadband oscillation uniform suppression method for offshore wind power flexible DC grid-connected systems as proposed in the above embodiments. The storage medium can be implemented by 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 Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0134] In summary, this invention achieves real-time signal characteristic data construction by performing feature analysis and classification on global parameters, followed by independent component analysis and frequency domain joint mapping. This not only enhances the decoupling and unification of multi-source signals but also provides a precise basis for subsequent regulation. Furthermore, by reconstructing energy flow through impedance synergistic tuning combined with port and transmission characteristics, and supplemented by nonlinear adjustment to generate port energy absorption parameters, energy sharing and dynamic absorption between ports are realized. This forms a uniform and synergistic oscillation suppression mechanism across the entire link, effectively improving the stability and reliability of offshore wind power flexible DC grid connection.

[0135] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for uniformly suppressing broadband oscillations in offshore wind power flexible DC grid-connected systems, characterized in that: include, Collect parameters of the entire domain of wind power flexible DC grid connection, and perform feature analysis and time-domain classification processing to generate broadband oscillation characteristic parameters; Multi-source signal decoupling and frequency domain joint mapping are performed on broadband oscillation characteristic parameters to generate real-time signal feature data; The real-time signal characteristic data is processed through impedance co-tuning and energy transfer path reconstruction to generate port energy absorption parameters. The specific steps are as follows. By performing port impedance co-tuning on real-time signal characteristic data, the optimal port impedance parameters can be obtained. By combining the optimal port impedance parameters with the electrical characteristics of each port and the transmission characteristics of the submarine cable, energy flow reconstruction and transmission path optimization are performed to generate port oscillation energy distribution. Energy partitioning analysis, impedance adjustment and phase-frequency coupling calculation are performed on the energy distribution of port oscillation to generate port energy absorption parameters; Asymmetric coupling attenuation and time-domain sequence renormalization are performed on the port energy absorption parameters to generate the electrical state parameters after port dissipation. The electrical state parameters after port dissipation are processed by a switch sequence to generate source-side spectrum optimization parameters. Power control and safety protection are applied to the source-end spectrum optimization parameters to generate oscillation suppression results.

2. The broadband oscillation uniformity suppression method for offshore wind power flexible DC grid-connected systems as described in claim 1, characterized in that: The specific steps for generating broadband oscillation characteristic parameters are as follows. Data synchronization, noise reduction filtering, and standardization are performed on the global parameters of wind power flexible DC grid connection to obtain unified global parameters. Signal decomposition and frequency energy analysis are performed on the unified global parameters to obtain oscillation energy distribution data for each frequency band. Multidimensional decomposition calculations are performed on the oscillation energy distribution data of each frequency band to extract instantaneous voltage, current, power and phase characteristics. Nonlinear integration and frequency-time domain coupling mapping are then performed to generate broadband oscillation characteristic parameters.

3. The broadband oscillation uniformity suppression method for offshore wind power flexible DC grid-connected systems as described in claim 1, characterized in that: The specific steps for generating real-time signal feature data are as follows. The broadband oscillation characteristic parameters are decoupled through independent component analysis to generate decoupled oscillation characteristic data; Frequency domain joint mapping and feature integration are performed on the decoupled oscillation characteristic data to generate real-time signal characteristic data.

4. The broadband oscillation uniformity suppression method for offshore wind power flexible DC grid-connected systems as described in claim 3, characterized in that: The specific steps for performing frequency domain joint mapping and feature integration on the decoupled oscillation characteristic data to generate real-time signal characteristic data are as follows. The instantaneous amplitude, phase, and frequency features of each port are extracted from the decoupled oscillation characteristic data, and then standardized using a unified scale to generate a normalized frequency domain feature vector. The normalized frequency domain feature vector is jointly processed by port coupling mapping and frequency interaction calculation to generate inter-port frequency domain interaction features. The port frequency domain interaction characteristics are integrated and nonlinearly normalized to generate real-time signal characteristic data.

5. The broadband oscillation uniformity suppression method for offshore wind power flexible DC grid-connected systems as described in claim 1, characterized in that: The specific steps for performing energy partitioning analysis, impedance adjustment, and phase-frequency coupling calculations on the port oscillation energy distribution to generate port energy absorption parameters are as follows. The instantaneous amplitude of each port is extracted from the energy distribution of port oscillation and nonlinearly mapped to generate amplitude adjustment information. Nonlinear coordinated adjustment of port impedance coupling is then performed to generate impedance adjustment information. Nonlinear phase and frequency composite calculations are performed on the impedance adjustment information to generate coupling correction information; The amplitude adjustment information, impedance adjustment information, and coupling correction information are combined and calculated to generate the port energy absorption parameters.

6. The broadband oscillation uniformity suppression method for offshore wind power flexible DC grid-connected systems as described in claim 1, characterized in that: The specific steps for generating the electrical state parameters after port dissipation are as follows. The port energy absorption parameters are differentially attenuated according to the oscillation coupling strength between ports to generate port attenuation characteristic values; The port attenuation characteristic values ​​are integrated by sliding window and normalized in the time domain to generate the electrical state parameters after port dissipation.

7. The broadband oscillation uniformity suppression method for offshore wind power flexible DC grid-connected systems as described in claim 1, characterized in that: The specific steps for generating the source-end spectrum optimization parameters are as follows: After the electrical state parameters of the port dissipate are matched by switching sequence coordination to obtain a coordinated switching control sequence, and then spectrum mapping is performed to generate a source-end frequency distribution feature matrix. Energy normalization and segmented mapping are performed on the source-end frequency distribution feature matrix to generate an optimized feature set of the source-end frequency band; Nonlinear fusion and coordinated adjustment processing is performed on the source-end frequency band optimization feature set to generate source-end spectrum optimization parameters.

8. The broadband oscillation uniformity suppression method for offshore wind power flexible DC grid-connected systems as described in claim 1, characterized in that: The specific steps for generating the oscillation suppression result are as follows. Power peak limiting and high-power band suppression are applied to the source-end spectrum optimization parameters to generate a controlled power reference, and nonlinear power adjustment is performed to obtain the power distribution vector; The power distribution vector is modified by safety constraints to generate a safety protection vector, and a composite power coupling operation is performed to obtain the oscillation suppression result.

9. A broadband oscillation uniform suppression system for offshore wind power flexible DC grid connection systems, based on the broadband oscillation uniform suppression method for offshore wind power flexible DC grid connection systems according to any one of claims 1 to 8, characterized in that: include, The parameter acquisition module is used to collect parameters of the entire domain of wind power flexible DC grid connection, and perform feature analysis and time-domain classification processing to generate broadband oscillation characteristic parameters; The signal decoupling module is used to decouple multi-source signals and perform frequency domain joint mapping on broadband oscillation characteristic parameters to generate real-time signal feature data. Impedance tuning module is used to process real-time signal characteristic data through impedance co-tuning and energy transmission path reconstruction to generate port energy absorption parameters. The attenuation and reshaping module is used to perform asymmetric coupling attenuation and time-domain sequence reshaping on the port energy absorption parameters to generate the electrical state parameters after port dissipation. The switch application module is used to process the electrical state parameters after port dissipation through a switch sequence to generate source-side spectrum optimization parameters. The power control and protection module is used to perform power control and safety protection processing on the source-end spectrum optimization parameters and generate oscillation suppression results.

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