Broadband oscillation uniform suppression method and system of offshore wind power flexible direct current grid-connected system

Abstract

The invention discloses a broadband oscillation uniform suppression method and system for an offshore wind power flexible direct current grid-connected system, and relates to the technical field of offshore wind power flexible direct current grid-connected control, and the method comprises the steps: carrying out the multi-source signal decoupling and frequency domain joint mapping of broadband oscillation characteristic parameters, and generating real-time signal characteristic data; performing impedance cooperative tuning and energy transmission path reconstruction processing on the real-time signal characteristic data to generate port energy absorption parameters; performing asymmetric coupling attenuation and time domain sequence reforming on the port energy absorption parameters to generate port post-dissipation electrical state parameters; processing the electrical state parameters after port dissipation through a switch sequence collaborative application to generate source end spectrum optimization parameters; after global parameters are subjected to feature analysis and classification, the construction of real-time signal feature data is realized by adopting independent component analysis and frequency domain joint mapping, so that not only is the decoupling and uniformity of multi-source signals enhanced, but also an accurate basis is provided 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 capability 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: 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; decoupling multi-source signals and jointly mapping frequency domain of the wideband oscillation characteristic parameters to generate real-time signal feature data; processing the real-time signal feature data through impedance collaborative 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 port dissipation electrical state parameters; The port dissipation electrical state parameters are processed through a switch sequence to generate source end spectrum optimization parameters; The source end spectrum optimization parameters are subjected to power control and safety protection processing to generate oscillation suppression results.

[0007] 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, 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; The unified global parameters are subjected to signal decomposition and frequency energy analysis to obtain frequency band oscillation energy distribution data; The frequency band oscillation energy distribution data are subjected to multi-dimensional decomposition calculation to extract instantaneous voltage, current, power and phase characteristics, and subjected to nonlinear integration and frequency-time domain coupling mapping processing to generate wideband oscillation characteristic parameters.

[0008] 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, The wideband oscillation characteristic parameters are decoupled through independent component analysis to generate decoupled oscillation characteristic data; The decoupled oscillation characteristic data are subjected to frequency domain joint mapping and feature integration to generate real-time signal characteristic data.

[0009] 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, The instantaneous amplitude, phase and frequency characteristics of each port are extracted from the decoupled oscillation characteristic data, subjected to unified scale standardization processing to generate normalized frequency domain feature vectors; The normalized frequency domain feature vectors are subjected to joint processing through port coupling mapping and frequency interaction calculation to generate port frequency domain interaction features; The port frequency domain interaction features are subjected to integration and nonlinear normalization processing to generate real-time signal characteristic data.

[0010] As a preferred scheme of the offshore wind power flexible direct current grid-connected system wideband oscillation uniform suppression method, the port energy absorption parameters are generated by the following specific steps, The real-time signal characteristic data are subjected to port impedance collaborative tuning to obtain optimal port impedance parameters; The optimal port impedance parameters are combined with the electrical characteristics of each port and the transmission characteristics of the submarine cable to perform energy flow reconstruction and transmission path optimization, and to generate port oscillation energy distribution; The port oscillation energy distribution is analyzed by energy partition, impedance adjustment and phase frequency coupling calculation to generate port energy absorption parameters.

[0011] As a preferred scheme of the wideband oscillation uniform suppression method of the offshore wind power flexible direct current grid-connected system, the port oscillation energy distribution is analyzed by energy partition, impedance adjustment and phase frequency coupling calculation to generate port energy absorption parameters, and the specific steps are as follows, 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; The impedance adjustment information is calculated by nonlinear phase and frequency to generate coupling correction information; The amplitude adjustment information, impedance adjustment information and coupling correction information are combined to generate port energy absorption parameters.

[0012] As a preferred scheme of the wideband oscillation uniform suppression method of the offshore wind power flexible direct current grid-connected system, the port dissipation after electrical state parameters are generated, and the specific steps are as follows, The port energy absorption parameters are subjected to differential attenuation processing according to the oscillation coupling strength between ports to generate port attenuation eigenvalues; The port attenuation eigenvalues are integrated by sliding window and processed by time domain normalization to generate port dissipation after electrical state parameters.

[0013] As a preferred scheme of the wideband oscillation uniform suppression method of the offshore wind power flexible direct current grid-connected system, the source end frequency spectrum optimization parameters are generated, and the specific steps are as follows, The port dissipation after electrical state parameters are matched with the switching sequence to obtain a cooperative switching control sequence, and the frequency spectrum mapping is performed to generate a source end frequency distribution feature matrix; The source end frequency distribution feature matrix is subjected to energy normalization and segmented mapping to generate a source end frequency band optimization feature set; The source end frequency band optimization feature set is subjected to nonlinear fusion and cooperative adjustment processing to generate source end frequency spectrum optimization parameters.

[0014] As a preferred scheme of the wideband oscillation uniform suppression method of the offshore wind power flexible direct current grid-connected system, the oscillation suppression result is generated, and the specific steps are as follows, The source end frequency spectrum optimization parameters are subjected to power peak value limitation and high power segment suppression processing to generate a controlled power reference, and nonlinear power adjustment is performed to obtain a power distribution vector; The power distribution vector is subjected to a security constraint correction process to generate a security protection vector, and a composite power coupling operation is performed to obtain an oscillation suppression result.

[0015] In a second aspect, the present application provides a wideband oscillation uniform suppression system for an offshore wind power flexible direct current grid-connected system, comprising a parameter acquisition module for acquiring wind power flexible direct current grid-connected global parameters and performing feature analysis and time domain classification processing to generate wideband oscillation characteristic parameters; A signal decoupling module is configured to perform multi-source signal decoupling and frequency domain joint mapping on the wideband oscillation characteristic parameters to generate real-time signal feature data. An impedance tuning module is configured to perform impedance collaborative tuning and energy transmission path reconstruction processing on the real-time signal feature data to generate port energy absorption parameters. An attenuation regularization module is configured to perform asymmetric coupled attenuation and time domain sequence regularization on the port energy absorption parameters to generate post-port dissipation electrical state parameters. A switch application module is configured to perform switch sequence collaborative application processing on the post-port dissipation electrical state parameters to generate source end spectrum optimization parameters. A power control protection module is configured to perform power control and security protection processing on the source end spectrum optimization parameters to generate an oscillation suppression result.

[0016] The present application has the following advantages: after feature analysis and classification of global parameters, independent component analysis and frequency domain joint mapping are used to construct real-time signal feature data, which not only enhances the decoupling and unity of multi-source signals, but also provides accurate basis for subsequent regulation; energy flow reconstruction is performed by impedance collaborative tuning combined with port characteristics and transmission characteristics, and port energy absorption parameters are generated by nonlinear regulation, which realizes energy sharing and dynamic absorption between ports, forms a uniform and collaborative oscillation suppression mechanism in the whole link range, and effectively improves the stability and reliability of offshore wind power flexible direct current grid-connected system. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0018] Fig. 1 Flow chart of the wideband oscillation uniform suppression method for offshore wind power flexible direct current grid-connected system.

[0019] Fig. 2 Schematic diagram of the wideband oscillation uniform suppression system for offshore wind power flexible direct current grid-connected system.

[0020] Fig. 3 Flow chart of the method for uniform suppression of wideband oscillation.

[0021] Fig. 4 Flow chart of the method for generating refined port energy absorption parameters. DETAILED DESCRIPTION

[0022] In order to make the above objectives, characteristics and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0023] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details given herein. In other instances, well-known methods have not been described in detail in order to avoid unnecessarily obscuring the present application. Therefore, the present application is not intended to be limited by the specific embodiments disclosed below.

[0024] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is independent or alternative to other embodiments.

[0025] REFERENCE Figs. 1-4 For one embodiment of the present application, the embodiment provides a method for uniform suppression of wideband oscillation of offshore wind power flexible grid connection system, comprising the following steps: S1, collect wind power flexible grid connection global parameters, and perform feature analysis and time domain classification processing to generate wideband oscillation characteristic parameters.

[0026] It should be noted that the wind power flexible grid connection global parameters include generator output, current and voltage, converter station port current, voltage, sea cable and bus electrical transmission characteristics, DC bus topology information and converter switch state.

[0027] S1.1, perform data synchronization, denoising filtering and standardization processing on the wind power flexible grid connection global parameters to obtain unified global parameters.

[0028] Further, the global original parameters such as current, voltage, topology and switch state are synchronously collected from multiple links such as wind turbine generator, converter station port, sea cable and bus; the collected data is uniformly processed in time reference to ensure the time sequence consistency of different source signals; then random interference and measurement error are removed through filtering and noise elimination method; the processed signals are normalized and structured in amplitude, phase and frequency dimensions to obtain unified global parameters.

[0029] S1.2, perform signal decomposition and frequency energy analysis on the unified global parameters to obtain oscillation energy distribution data of each frequency band.

[0030] Further, the signal components in the unified global parameters are classified and identified, and corresponding time series data are extracted according to the response characteristic differences of current signals, voltage signals and power signals in the sampling waveform. In the decomposition process, the data streams of different signal channels are independently separated according to the source channels and physical properties of the measurement signals, for example, the voltage channel data is extracted as a voltage time series, the current channel data is extracted as a current time series, and the power channel data is extracted as a power time series, so as to realize channel decomposition of the unified global parameters. The extracted time domain waveforms are subjected to feature filtering and noise suppression processing to obtain independent feature components of each channel. Based on fast Fourier transform or multi-resolution time-frequency decomposition method, the decomposition signals are 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 of different frequency intervals is counted and classified to obtain the oscillation energy distribution of each frequency band.

[0031] S1.3, multi-dimensional decomposition calculation is performed on the oscillation energy distribution data of each frequency band to extract instantaneous voltage, current, power and phase characteristics, and nonlinear integration and frequency-time domain coupling mapping processing are performed to generate wideband oscillation characteristic parameters.

[0032] Further, each frequency band signal is separated in time and frequency domain by Fourier transform or wavelet transform, and instantaneous voltage, instantaneous current, instantaneous power and phase characteristics are extracted. The extracted instantaneous voltage, instantaneous current, instantaneous power and phase characteristics are nonlinearly integrated, and the integrated instantaneous voltage, instantaneous current, instantaneous power and phase characteristics are subjected to amplitude square, phase coupling or power normalization processing, and frequency-time domain coupling mapping processing. The corresponding relationship in different frequency bands and time domain windows is established according to the energy concentration degree, phase continuity and amplitude change trend of the signal, and the matching relationship between the characteristics of each frequency band and the time interval is determined, so as to realize the synchronous association and coupling fusion of time domain characteristics and frequency domain characteristics. The time domain characteristics and frequency domain characteristics are fused to generate wideband oscillation characteristic parameters that can reflect the wideband oscillation characteristics and maintain the time-frequency correlation.

[0033] S2, multi-source signal decoupling and frequency domain joint mapping are performed on the wideband oscillation characteristic parameters to generate real-time signal feature data.

[0034] S2.1, the wideband oscillation characteristic parameters are decoupled by independent component analysis to generate decoupled oscillation characteristic data.

[0035] Further, the broadband oscillation characteristic parameters are organized into a two-dimensional matrix in time sequence, each row representing a complete characteristic vector of voltage, current, power and phase at a time point, and each column representing the change of each dimension characteristic in the entire time sequence; the dimension difference is eliminated through mean removal and covariance standardization; independent component analysis is applied to the standardized two-dimensional matrix, the two-dimensional matrix is decomposed into several statistically independent components by assuming that each source signal is independent, and each component is linearly reconstructed, and the corresponding components in the voltage, current, power and phase dimensions are recombined in the original characteristic space according to the mixing matrix and separation matrix parameters obtained by independent component analysis, to strip the coupling effect between different source signals, and obtain decoupled oscillation characteristic data.

[0036] S2.2, 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 characteristic vectors.

[0037] Further, instantaneous amplitude, phase and frequency characteristics are extracted from the decoupled oscillation characteristic data for each port to form a complete frequency domain characteristic set of each port at the current time point; unified scale processing is performed on characteristics of different ports and different types (such as voltage characteristics, current characteristics, power characteristics and phase characteristics), including amplitude normalization, phase mapping to a unified angle range, and frequency characteristic standardization, to eliminate dimension difference and amplitude difference; the processed characteristics of each port are integrated into normalized frequency domain characteristic vectors in time sequence.

[0038] S2.3, the normalized frequency domain characteristic vectors are jointly processed through port coupling mapping and frequency interaction calculation to generate inter-port frequency domain interaction characteristics.

[0039] Further, the normalized frequency domain characteristic vectors are arranged according to the port index to form a port characteristic matrix; according to the physical coupling relationship (such as electrical connection, impedance coupling and transmission path) between the ports, the characteristics of each port are mapped and processed with related port characteristics to establish a coupling relationship matrix between the ports; interaction calculation is performed in the frequency dimension to consider the mutual influence and coupling between different frequency components, and amplitude, phase and frequency information are integrated through nonlinear function or matrix operation to generate inter-port frequency domain interaction characteristics.

[0040] S2.4, the port frequency domain interaction characteristics are integrated and nonlinearly normalized to generate real-time signal characteristic data.

[0041] Further, the inter-port frequency domain interaction features are summarized according to the port and frequency dimensions to form a global feature matrix of the port; the amplitude, phase and frequency information in the matrix is subjected to nonlinear normalization processing, different port and frequency features are mapped to a unified scale, and the dimensional difference and extreme value influence are eliminated; in the normalization process, the response of important features is enhanced through a nonlinear function, while abnormal fluctuations are suppressed, thereby realizing feature smoothing and enhancement; real-time signal feature data is obtained.

[0042] It should be noted that the important features refer to key parameters that have a significant impact on oscillation characteristics and energy transmission in the inter-port frequency domain interaction process, mainly including feature components with large amplitude variation, obvious phase shift or prominent frequency fluctuation. These feature components usually reflect the main sources of changes in inter-port energy coupling strength, oscillation stability and power transmission efficiency, and are highlighted in the normalization and nonlinear enhancement process to highlight the dominant role in the overall oscillation behavior.

[0043] S3, the real-time signal feature data is subjected to impedance collaborative tuning and energy transmission path reconstruction processing to generate port energy absorption parameters.

[0044] The existing method usually processes the real-time signal feature data through single-port impedance matching or local damping control, focuses on the energy absorption efficiency of a single port, and reduces local oscillation by adjusting the port impedance or damping parameters, but in the case of multi-port coupling and complex energy transmission path, it is difficult to achieve global collaborative optimization, the inter-port oscillation energy distribution cannot be precisely controlled, and the energy absorption effect has limitations.

[0045] The present application processes the real-time signal feature data through port impedance collaborative tuning and energy transmission path reconstruction, and the instantaneous amplitude, phase and frequency features of each port gradually tend to a global optimal state under iterative adjustment, while the oscillation energy is reconstructed in combination with the inter-port impedance coupling and energy transmission path to generate port energy absorption parameters, realizing multi-port collaborative energy absorption and global oscillation suppression, and accurately controlling the inter-port energy distribution.

[0046] S3.1, the real-time signal feature data is subjected to port impedance collaborative tuning to obtain optimal port impedance parameters.

[0047] Further, the real-time signal feature data is organized into a port feature matrix according to the port order, each row representing the instantaneous amplitude, phase and frequency features of a single port at different frequencies, and each column representing the instantaneous features of different ports at the same frequency; the port feature matrix is subjected to collaborative tuning processing, including impedance matching adjustment of the port instantaneous amplitude, calculation of the phase correction amount of each port through impedance coupling relationship, and the expression is: ; wherein, representing the phase correction amount of each port, representing the instantaneous amplitude of the current port, representing the instantaneous amplitude of the adjacent port, representing the self-resistance of the port, representing the coupling resistance between the port and the adjacent port, representing the coupling reactance between the port and the adjacent port, representing the conversion of amplitude difference and impedance effect into phase adjustment amount; iteratively adjusting the impedance interaction between the ports in combination with the frequency characteristics; in the iterative process, the port impedance parameters tend to be globally optimal by continuously updating the port amplitude and phase characteristics, so as to obtain optimal port impedance parameters.

[0048] S3.2, combining the optimal port impedance parameters with the electrical characteristics of each port and the transmission characteristics of the submarine cable, reconstructing the energy flow and optimizing the transmission path to generate the port oscillation energy distribution.

[0049] Furthermore, the optimal port impedance parameters are associated 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; in the energy flow reconstruction process, the instantaneous energy flow direction and distribution of each port are calculated according to the impedance and electrical connection relationship between the ports, the optimal path is determined according to the conditions of minimum energy transmission loss, highest impedance matching degree and minimum phase difference, the path with the most balanced energy transfer and the least loss is selected as the optimal path by comparing the energy attenuation rate and power stability under different paths, so that energy is distributed along the optimal path to realize uniform transfer of oscillation energy between ports; in the transmission path optimization process, the energy flow path and impedance matching between ports are continuously corrected according to the characteristics of each port and the submarine cable to ensure balanced distribution of energy flow at different frequencies, and the port oscillation energy distribution is generated.

[0050] It should be noted that the electrical characteristics of each port are obtained by collecting the current, voltage, power and port topology information of the converter station; the transmission characteristics of the submarine cable are obtained by collecting the length, cross-section, resistance, reactance and electromagnetic transmission delay of the submarine cable.

[0051] The electrical characteristics of each port refer to the dynamic properties of voltage, current, power, phase and impedance exhibited by each port during energy transmission and oscillation, which reflect the response characteristics of the port to energy flow at different frequencies. The real-time electrical signals of the port are collected by using high-precision sensors, the electrical response values of the port at each frequency band are calculated through time-frequency analysis and parameter identification, and the port electrical characteristic parameters for energy flow reconstruction are obtained by fitting and correcting the historical operation data.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] S3.4 Perform nonlinear phase and frequency composite calculations on the impedance adjustment information to generate coupling correction information.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] S3.5. Combine the amplitude adjustment information, impedance adjustment information and coupling correction information to generate port energy absorption parameters.

[0064] 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.

[0065] 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.

[0066] "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.

[0067] "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.

[0068] 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.

[0069] S4.1. The port energy absorption parameters are differentially attenuated according to the oscillation coupling strength between ports to generate port attenuation characteristic values.

[0070] 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.

[0071] 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.

[0072] S4.2 Perform sliding window integration and time-domain normalization on the port attenuation characteristic values ​​to generate electrical state parameters after port dissipation.

[0073] 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.

[0074] S5. The electrical state parameters after port dissipation are processed by the switching sequence to generate source-side spectrum optimization parameters.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] S6. Perform power control and safety protection processing on the source-end spectrum optimization parameters to generate oscillation suppression results.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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; 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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; Real-time signal characteristic data is processed through impedance co-tuning and energy transmission path reconstruction 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 generating the port energy absorption parameters 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 zoning analysis, impedance adjustment, and phase-frequency coupling calculations are performed on the energy distribution of port oscillations to generate port energy absorption parameters.

6. The broadband oscillation uniformity suppression method for offshore wind power flexible DC grid-connected systems as described in claim 5, 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.

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 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.

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 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.

9. 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.

10. A broadband oscillation uniformity suppression system for offshore wind power flexible DC grid connection systems, based on the broadband oscillation uniformity suppression method for offshore wind power flexible DC grid connection systems according to any one of claims 1 to 9, 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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