126 results about "Impedance properties" patented technology

According to the power cable multi-defect nondestructive testing method and system based on the broadband impedance spectrum, impedance characteristics of a cable under different frequencies are measured, frequency domain data are converted into time domain data through inverse Fourier transform, and accurate positioning and evaluation of internal defects of the cable are achieved; the invention discloses a power cable multi-defect nondestructive testing method based on a broadband impedance spectrum. The method comprises the following steps: step 1, signal output and acquisition; the method comprises the steps that a broadband impedance spectrum tester is used for outputting a broadband sine wave voltage signal, frequency domain measurement data are collected, and the frequency domain measurement data are impedance data of a cable under different frequencies; 2, carrying out time-frequency conversion; converting the frequency domain measurement data into time domain data through inverse Fourier transform, generating a time-amplitude curve, and analyzing the electrical characteristics of the cable; 3, establishing a defect identification model; analyzing the electrical characteristics of the cable at different frequencies by using the transmission line model, and evaluating the state of the cable; step 4, defect positioning and evaluation; and 5, displaying and analyzing a result.

The invention discloses an impedance characteristic remodeling method, device and equipment and a medium, and is applied to the field of wind turbine generators. Wherein the corresponding rotor reference current is determined according to the electromagnetic reactive power, the active power and the corresponding power reference value; correcting the rotor current according to the rotor reference current by adopting a virtual admittance control mode, and generating a corresponding rotor voltage given value; sequentially performing differentiation, filtering and signal extraction processing on the rotor reference current and the rotor current to obtain an impedance remodeling signal; and correcting the rotor voltage given value based on the impedance remodeling signal so as to enable the corrected rotor voltage given value to serve as the control voltage of a rotor side converter in the medium-voltage doubly-fed wind turbine generator after impedance characteristic remodeling. The virtual admittance control mode and the impedance remolding signal mode are adopted to suppress the negative resistance effect of the rotor side converter in the medium-voltage doubly-fed wind turbine generator under voltage disturbance, and therefore the damping effect on external excitation in the sub-super-synchronous frequency band and the high frequency band is higher.

The invention relates to a multi-frequency bioelectrical impedance-based body fat accurate measurement method and system. The method comprises the following steps: receiving a mode selection instruction sent by a user to determine a current working mode; if the mode is a rapid measurement mode, applying single reference frequency and reference current intensity excitation, obtaining a single group of bioelectrical impedance data, and calculating a rapid body fat rate result; if the measurement mode is an accurate measurement mode, acquiring bioelectrical impedance data under a plurality of preset frequencies and a plurality of preset current intensities through a complete electrode system, performing signal processing on the data, extracting impedance amplitude and phase information, constructing an impedance characteristic curve, extracting characteristic parameters related to the body fat rate from the impedance characteristic curve, and calculating the body fat rate based on the characteristic parameters. And obtaining a final body fat rate result of the accurate measurement mode. According to the method, the body fat rate can be accurately measured, and the accuracy and reliability of a measurement result are improved.

The invention discloses an energy storage power station oscillation risk monitoring method and device based on impedance network aggregation, and belongs to the field of power systems, and the method comprises the steps: obtaining impedance information and a first network topology structure of each device in an energy storage power station; obtaining a first impedance network framework by adopting a hierarchical calculation method; based on the framework and the impedance information, an impedance network aggregation method is adopted to calculate impedance characteristics of all frequency points to form full-frequency-domain impedance characteristics, and the oscillation risk of the energy storage power station is monitored according to the full-frequency-domain impedance characteristics and actual impedance data. The problem that it is difficult to accurately monitor the oscillation risk of the energy storage power station while guaranteeing the calculation efficiency in the prior art can be solved.

The invention relates to the field of chip detection, and discloses a high-efficiency chip detection system and method, which are used for realizing long-term performance degradation detection of a chip. Comprising the following steps: synchronously acquiring power pin electric signals and chip surface thermal imaging data to generate an electrothermal coupling characteristic data set in a working state of a to-be-tested chip, and extracting impedance and heat conduction characteristic parameters through impedance spectroscopy analysis and thermal time constant calculation. And analyzing an internal signal transmission path based on impedance characteristic parameters to obtain path characteristic parameters, establishing a mathematical model of dynamic current and working voltage of the chip by combining the two, generating a system identification result, and finally generating a chip detection result and fault positioning information by integrating various parameters. According to the invention, system benchmark testing and environmental interference monitoring and compensation are carried out, and high precision and high robustness of a detection result are realized.

The invention discloses a cable high-frequency impedance characteristic analysis method based on bipolar trapezoidal wave excitation, and belongs to the technical field of power equipment state monitoring and fault diagnosis. In order to solve the problems of low test efficiency, insufficient high-frequency parameter modeling precision and weak anti-interference capability in cable high-frequency impedance characteristic analysis of a traditional sine wave excitation method, the method comprises the following steps: generating an odd-symmetry bipolar trapezoidal wave excitation signal with specific frequency and amplitude, and injecting the signal into the head end of a cable to be tested through a coupling device after power amplification; synchronously acquiring a high-frequency response signal of the key position of the cable under the excitation of the bipolar trapezoidal wave by using a data acquisition system; preprocessing the high-frequency response signal, converting the high-frequency response signal into a frequency domain through Fourier transform, calculating input impedance of the cable under different harmonic frequencies, and synthesizing a broadband impedance spectrum; based on the broadband impedance spectrum, the amplitude-frequency characteristic and the phase-frequency characteristic of impedance are analyzed, and cable state evaluation, partial discharge detection, insulation defect diagnosis or fault point positioning are realized. The method is used for an electric power system.

The invention relates to an electrical equipment insulation aging evaluation and early warning method and system capable of predicting maintenance, and belongs to the technical field of electrical engineering and automation. The method comprises the following steps: acquiring insulation state data of electrical equipment, establishing a performance-aging curve, analyzing local aging characteristics through an insulation tolerance test to obtain insulation deterioration degree data, constructing an insulation deterioration prediction framework, and generating an operation record containing insulation steady state evaluation and a discharge form, insulation maintenance information is configured in combination with a maintenance efficiency index to form an insulation deterioration evaluation scheme, spectrum analysis, impedance characteristic analysis and hot area layout identification are performed on an insulation state, an insulation material attenuation period is verified by using a dielectric frequency domain response technology, and equipment aging early warning information is obtained. And when the prediction track meets the maintenance efficiency index, the insulation attenuation parameter is updated, and the self-adaptive iteration of the insulation degradation prediction framework is realized, so that the prediction precision and the maintenance timeliness of the insulation aging of the electrical equipment are improved.

The invention provides a passive and active self-adaptive impedance reconstruction control method of a doubly-fed converter, which adopts a staged mixed damping strategy: before a stator is connected to a grid, a passivity-based parallel LC resonance suppressor is adopted to provide inherent broadband passive damping for a system. After a stator is connected to a grid, grid-side self-adaptive trapped wave active damping control based on online impedance identification is switched, and specific harmonic peaks caused by interaction of background harmonic waves and impedance of a power grid are accurately suppressed by sensing impedance characteristics of the power grid in real time and dynamically adjusting parameters of a wave trap. The passive active self-adaptive impedance reconstruction control method for the doubly-fed converter has the beneficial effects that the passive active self-adaptive impedance reconstruction control method for the doubly-fed converter has the function of comprehensively inhibiting the resonance risk caused by interaction between a doubly-fed wind turbine generator and a power grid in a broadband range. The technical problem that in the prior art, a damping frame which is in adaptive cooperation with the operation state of the double-fed system cannot be constructed is solved.

The invention discloses a dynamic test method and system for tissue frequency domain impedance characteristics, and belongs to the technical field of medical detection. The system comprises an energy generator, a bipolar scalpel, a signal generator, a radio frequency power amplifier module, a control unit, two loop switches, a sampling probe and a test unit. An electrode of the bipolar scalpel is used for being in contact with a biological tissue to be subjected to frequency domain impedance characteristic testing; the energy generator is connected with the first loop switch and is used for outputting an electric resection / electrocoagulation signal to the biological tissue so as to dynamically reproduce the state change of the biological tissue; and the signal generator inputs a broadband excitation voltage signal to the biological tissue through the radio frequency power amplifier module and the second loop switch. The control unit is used for coordinating on-off of the two loop switches. The sampling probe is used for collecting voltage and current signals of the double electrodes in real time and feeding back the signals to the testing unit. The test unit generates a real-time impedance characteristic spectrogram of the biological tissue along with frequency change. The tissue impedance change can be monitored on line in real time.

The invention discloses a tissue broadband domain impedance characteristic test system and method, and belongs to the technical field of medical detection. The system comprises a signal acquisition and control unit, a radio frequency power amplifier module, a protective resistor, a bipolar scalpel, two voltage probes and a sampling resistor module, an electrode of the bipolar scalpel is in contact with a biological tissue to be subjected to impedance characteristic test; the signal acquisition and control unit outputs a broadband excitation voltage signal, the broadband excitation voltage signal is amplified by the radio frequency power amplifier module, and the amplified signal sequentially passes through the protective resistor, the sampling resistor module and the electrode to be input into biological tissue; the two voltage probes are respectively used for sampling voltage signals of the electrode and the sampling resistor module in real time and feeding back the voltage signals to the signal acquisition and control unit; and the signal acquisition and control unit obtains impedance amplitudes and impedance phases of the biological tissue under various frequencies through Fourier transform, and impedance characteristic testing is completed. Data support can be provided for the design of the energy surgical instrument.

The invention discloses a new energy grid-connected inverter parameter identification method fusing time-frequency domain dynamic characteristics, and the identification process is divided into three stages: a time domain identification stage, a frequency domain identification stage and a time-frequency domain characteristic verification stage. According to the method, a new energy grid-connected inverter impedance characteristic curve database is established by combining time domain and frequency domain operation characteristic curves of a new energy grid-connected inverter'white box model 'of a known control strategy, and the operation characteristic curve in the impedance characteristic curve database is compared with the operation characteristic curve of a new energy grid-connected inverter'black box model'. And the control mode conforming to the operation characteristics of the new energy grid-connected inverter is identified and obtained. Compared with an existing new energy inverter parameter identification method, the new energy inverter parameter identification method has the advantages that the modeling process of the new energy inverter is simplified, and the new energy inverter parameter identification efficiency is greatly improved; and the input of a new control strategy is supported, and a guarantee is provided for the identification range and precision of the impedance characteristic curve database.

The invention relates to the technical field of power grid strength influence evaluation, in particular to a method and system for analyzing the influence of an equipment control structure on the power grid strength, and the method comprises the steps: building control structures of network following type GFL and network construction type GFM power electronic equipment, and carrying out the comparative analysis of the impedance characteristics of the GFL and GFM power electronic equipment through a small signal analysis method; establishing an impedance analysis model of the GFL and GFM power electronic equipment; verifying the correctness of the impedance analysis model by using a comparative analysis method; quantitatively analyzing the influence of the control structures of the GFL and GFM power electronic equipment on the impedance characteristics; and judging the influence of the GFL and GFM power electronic equipment on the power grid strength according to the quantitative analysis result. According to the method, the problem of analysis of the influence of different control structures on the impedance characteristics of the GFL and GFM power electronic equipment and the influence of different equipment on the power grid strength is effectively solved, and the influence of control structures such as a synchronous link and a voltage and current double loop on the impedance characteristics is revealed.

The invention discloses a multi-frequency electromagnetic detection signal generation method for composite material defect detection, and relates to the technical field of electromagnetic detection, and the method comprises the following steps: based on composite material structure layering, collecting response voltages of a composite material defect-free standard sample under different excitation frequencies, different structure layers and different directions; carrying out normalization processing on the response voltage, and calculating through an Ohm law to obtain an impedance characteristic curve of the composite material; finding an optimal frequency excitation point from the impedance characteristic curve, and calculating an impedance matching coefficient according to the optimal frequency excitation point; and probe calibration is carried out based on the impedance matching coefficient, and multi-frequency composite information is generated and output to an excitation coil of the excitation probe. Impedance matching of the composite material, the excitation coil and the differential coil is realized.

The invention discloses an automatic simulation modeling method and verification method for impedance characteristics of a new energy unit and an electromagnetic transient simulation model used for the new energy unit. The simulation verification method comprises the steps that a frequency scanning range is determined, frequency sweeping is conducted on the electromagnetic transient simulation model, and disturbance excitation voltage phasors are injected into the electromagnetic transient simulation model; executing simulation on the electromagnetic transient simulation model, and acquiring a response current phasor under the condition of injecting the disturbance excitation voltage phasor; calculating positive sequence impedance and negative sequence impedance according to the disturbance excitation voltage phasor and the response current phasor; constructing an impedance matrix; and according to the impedance matrix, performing comparison verification with actually measured impedance characteristic data of the new energy unit, and calculating an average relative error, thereby verifying the electromagnetic transient simulation model of the new energy unit. The technical problem that whether the result of the simulation model of the new energy unit is accurate or not cannot be judged due to the fact that the simulation verification correctness of frequency scanning cannot be automatically verified is solved.

The invention relates to a DC measuring device transmission characteristic MMC impedance modeling method comprising the following steps: constructing a difference and common mode time domain small signal model of an MMC main circuit based on the Kirchhoff voltage law; a coupling rule is obtained according to the frequency coupling characteristic and the phase sequence coupling mechanism of the difference and common mode time domain small signal model; converting the difference and common mode time domain small signal model into an HSS-MMC main circuit model according to a coupling rule; establishing each control HSS model according to the MMC control loop structure; deriving a transfer function model of the DC voltage measurement device to update the DC voltage control HSS model; combining each control HSS model and the modulation wave expression to obtain an MMC control system HSS model; the HSS-MMC main circuit model and the MMC control system HSS model are combined to obtain an MIMO admittance model; obtaining an SISO equivalent impedance model of the MMC according to the power grid impedance expression and the MIMO admittance model; and according to MMC system parameters and different frequency disturbance control gains, an SISO impedance model of the MMC is utilized to solve an impedance analytic value. And the MMC high-band impedance characteristic can be accurately described.

The embodiment of the invention provides a cable early-stage fault positioning method and device based on metal sheath parameters. The cable early-stage fault positioning method based on the metal sheath parameters comprises the steps that a cable electrical model is established based on electrical parameters; obtaining a key electrical quantity, comparing the key electrical quantity with a preset threshold value, and determining a comparison result; determining fault feature information based on the comparison result; and determining a fault point based on the fault feature information and the fault positioning equation. According to the scheme, the impedance characteristic of the cable metal sheath is utilized, and the parameters of the metal sheath are introduced into a fault positioning algorithm. According to the method, the positioning error is effectively reduced, the accuracy of the early fault positioning process is remarkably improved, and a more efficient and more accurate solution is provided for solving the detection and positioning problems of the power system in the early stage of the fault.

The invention relates to the technical field of microwaves, in particular to a broadband antenna matching system based on a 4: 1 impedance conversion balun, which comprises the 4: 1 impedance conversion balun, an adjustable impedance matching network, a radio frequency monitoring unit and a logic control unit, the logic control unit is configured to receive forward power and reflection power signals and calculate to obtain a standing-wave ratio or a reflection coefficient under a current working frequency point; comparing the standing-wave ratio or the reflection coefficient with a preset threshold value; based on a comparison result, executing an adaptive matching algorithm, and iteratively generating and outputting a new digital control signal to drive a variable reactance element in the adjustable impedance matching network to change the value of the variable reactance element; and through closed-loop feedback control, the impedance of the adjustable impedance matching network is dynamically optimized. By modifying an algorithm parameter or a lookup table in the logic control unit, the same hardware platform can easily adapt to antennas with different impedance characteristics and different frequency bands. And the design flexibility and the product universality are greatly enhanced.

The invention relates to the field of power systems, in particular to a multi-power-supply system broadband oscillation risk testing and evaluating method. The method comprises the following steps: accessing a new energy physical controller to a semi-physical simulation platform, injecting a sweep frequency voltage disturbance signal, and collecting the signal to generate a semi-physical three-dimensional impedance matrix; constructing a corresponding single-machine electromagnetic model in electromagnetic transient simulation software, and injecting sweep-frequency voltage disturbance to generate a single-machine impedance characteristic curve; comparing the two, and correcting electromagnetic model control parameters according to a deviation frequency band; and finally, combining the corrected models and the like, injecting a sweep frequency disturbance signal at a grid-connected point, obtaining impedance, and evaluating the oscillation risk according to a Nyquist stability criterion. According to the method, a semi-physical simulation platform and electromagnetic transient simulation software are combined, impedance scanning is carried out on a physical controller, comparison verification and parameter correction are carried out on the physical controller and an electromagnetic model, the problem of large difference between the model and an actual system is effectively solved, and the accuracy and reliability of broadband oscillation risk assessment are remarkably improved.

The invention provides a wide-temperature high-frequency high-impedance manganese zinc ferrite material and a preparation method thereof, and relates to the technical field of magnetic materials. The manganese zinc ferrite material comprises main components and auxiliary components, the main components comprise Fe2O3, ZnO, Mn3O4 and MgO, and the auxiliary components comprise Na2O, Co2O3, Li2O and K2O; the high-frequency high-impedance manganese-zinc ferrite material with the wide-temperature characteristic provided by the invention has the characteristics of high magnetic conductivity and high resistivity, is good in high-frequency impedance characteristic, relatively stable in magnetic conductivity and high-frequency impedance at the temperature of-40 to 120 DEG C, small in temperature influence change, and capable of stably working in an environment with sudden temperature change; and stable and safe operation of instruments and equipment is ensured.

The present application relates to a method for modeling the transfer characteristics of a DC measurement device using MMC impedance. The method comprises: constructing a differential and common-mode time-domain small-signal model of the MMC main circuit based on Kirchhoff's voltage law; deriving a coupling law based on the frequency coupling characteristics and phase sequence coupling mechanism of the differential and common-mode time-domain small-signal model; converting the differential and common-mode time-domain small-signal model into an HSS-MMC main circuit model based on the coupling law; establishing various control HSS models based on the MMC control loop structure; deriving a transfer function model of the DC voltage measurement device to update the DC voltage control HSS model; combining the various control HSS models with a modulation wave expression to obtain an MMC control system HSS model; jointly combining the HSS-MMC main circuit model and the MMC control system HSS model to obtain a MIMO admittance model; obtaining a SISO equivalent impedance model of the MMC based on the grid impedance expression and the MIMO admittance model; and solving an impedance analytical value using the MMC SISO impedance model based on MMC system parameters and control gains for different frequency disturbances. The method accurately describes the high-frequency impedance characteristics of the MMC.

The invention discloses a test platform and a test method for LCC-SS-T topology based on impedance characteristic identification. The test platform and the test method are high in test efficiency, capable of avoiding mutual interference of parameters and accurate in judgment. The invention discloses a test platform for an LCC-SS-T topology based on impedance characteristic identification. The test platform comprises the LCC-SS-T topology formed by a primary side resonance assembly to be tested and a secondary side resonance assembly to be tested; the primary side inverter is used for outputting a driving waveform with the frequency of 40k-200kHz and is used for driving the LCC-SS-T topology to complete a test process; the PFC module is used for being connected with a power grid for power factor correction, converting alternating current of the power grid into direct current and inputting the direct current into the primary side inverter; the secondary side test load module is used for receiving energy transmitted from the primary side by the test platform; and the test equipment is used for receiving and calculating the midpoint voltage and the resonance current of the primary side to-be-tested resonance assembly and the midpoint voltage and the resonance current of the secondary side to-be-tested resonance assembly, and further calculating the impedance. The invention is applied to the technical field of wireless charging.

The invention relates to the technical field of new energy power systems, in particular to a modeling method and device for a nonlinear frequency domain coupling impedance model of a new energy grid-connected system. The method comprises the steps of establishing an impedance model of the single-machine converter, analyzing a frequency sweeping result of the single-machine converter obtained in the impedance model establishing process according to the multi-time scale characteristic of a controller, obtaining an impedance characteristic analysis result of each frequency band, analyzing corresponding parameters of the impedance model under different frequency bands according to the impedance characteristic analysis result of each frequency band, and calculating the impedance model of the single-machine converter according to the parameters. According to the obtained impedance transfer function and parameters of each frequency band, establishing an output impedance mathematical model of the inverter under all working conditions; according to the output impedance mathematical model, the feeder equivalent impedance of the feeder from the tail end to the head end is determined, and the overall output impedance of the multiple parallel feeder lines at the collection cabinet is calculated. According to the method, the problems that a multi-dimensional coupling mechanism is not clear and the equivalent modeling precision needs to be improved in the process of expanding the single machine characteristics to the whole station level in the prior art can be solved.

The invention provides an EPS system short-time overcurrent protection method, device and equipment and a storage medium, and belongs to the technical field of EPS system control, and the method comprises the steps: S1, when a real-time current is greater than a preset current threshold value, executing steps S2-S5; s2, calculating a current change rate; s3, generating a Vds voltage reasoning threshold value; s4, working condition parameters are obtained, working condition correction factors are determined, and the Vds voltage reasoning threshold value is corrected; s5, the Vds voltage is compared with the Vds voltage reasoning threshold value; and S6, repeatedly executing the steps S2-S5, and cutting off the driving circuit when the fault frequency is greater than a first preset frequency threshold. According to the short-time overcurrent protection method, device and equipment for the EPS system and the storage medium provided by the invention, the influence of impedance characteristic change and parasitic inductance of a power loop on a judgment result can be effectively prevented, so that the false alarm probability is reduced.

The invention discloses a biological high-frequency electrical impedance characteristic real-time acquisition method and system, and the method comprises the steps: transmitting a high-frequency excitation signal to a first electrode pair through a coaxial shielding line, and obtaining a voltage signal U0 of a sampling resistor R0 connected in series with a signal transmission loop of the first electrode pair; a signal transmission loop of the electrode pair I is connected with a contact resistor RL in series to form an RC filter circuit together with the coaxial shielding line, and passive RC compensation is arranged between the electrode pair I and the living body; the voltage UZ on the impedance of the living body is obtained by the coaxial shielding line through the electrode pair II, and passive RC compensation is arranged between the electrode pair II and the living body; according to the sampling resistance R0, the voltage U0 and the voltage UZ, the bioelectrical impedance value RZ of the to-be-measured organism is calculated.

The method for modeling impedance of DAB converter based on multi-LC resonant unit and predicting high-frequency oscillation frequency comprises the following steps: step 1, measuring impedance characteristics of a high-frequency transformer and an external inductor according to a determined DAB converter topology; step 2, calculating parasitic parameters of the high-frequency transformer and the external inductor according to the measurement results of the impedance characteristics; and step 3, judging the number of high-frequency oscillation frequencies for different configurations and parameter sizes of the external inductor and the leakage inductance of the high-frequency transformer, and selecting a high-frequency oscillation frequency prediction formula to obtain a result. The frequency variation effects of the external inductor and the leakage inductance of the high-frequency transformer are comprehensively considered, the parasitic parameters are effectively extracted through accurate modeling, and the oscillation prediction formula is derived based on the transfer function, so that the deep physical mechanism of the high-frequency oscillation is revealed, and systematic and guiding theoretical basis and engineering practice support are provided for the high-frequency oscillation suppression scheme under different structural topologies and parameter combinations.

The application relates to a wire harness radiation simulation method and system based on the impedance frequency response characteristics of a magnetic ring, and the method comprises the following steps: selecting measuring points around an electromagnetic simulation coupling model of a magnetic ring, a wire harness and a metal structure around the wire harness; inputting an excitation condition data and a magnetic ring impedance characteristic notebook document to perform simulation analysis, obtaining a first electric field radiation value of the measuring points changing with frequency curve diagram, the above process does not need to set the magnetic ring in the actual vehicle for verification, the impedance frequency response characteristic curve of the magnetic ring is converted into an impedance characteristic notebook document, so that the electric field radiation value of the measuring points under different frequencies after the magnetic ring of the specification type is set is obtained; in addition, the specification and the installation position of the magnetic ring can be modified, and then simulation is performed again, so that the specification and the installation position of the magnetic ring meeting the requirements are quickly determined, and the test time is reduced; the simulation analysis result gives a reference for modifying and adjusting the specification and the installation position, avoids randomness of modification, and provides certain guidance for rectification of electromagnetic radiation exceeding of a direct current fast charging wire harness.

The present invention discloses a harmonic suppression method based on virtual impedance collaborative control, which relates to the field of power grid harmonic control technology and is used to solve the technical problems of strong time-varying harmonics, high energy consumption, and parameter fixation in high-penetration photovoltaic scenarios. The method comprises: obtaining the original electrical signal, impedance parameters, and filtering parameters on the grid side; performing real-time phase correction based on the original electrical signal to obtain multi-band harmonic frequencies; constructing a virtual impedance based on the multi-band harmonic frequencies, and generating an impedance characteristic matrix based on the impedance parameters and filtering parameters; using the impedance characteristic matrix to perform parameter optimization of the virtual impedance based on deep reinforcement learning to obtain the optimal virtual impedance parameters; and changing the equivalent output impedance of the inverter through the virtual impedance under the optimal virtual impedance parameters to achieve harmonic suppression.

The invention discloses an MMC impedance prediction method and system of a flexible interconnection system, equipment, a medium and a product, and the method comprises the steps: injecting positive and negative sequence voltage disturbances with different voltage frequencies into a pre-constructed MMC simulation model of a network construction type flexible interconnection system under a plurality of different working condition variables; the method comprises the steps of obtaining output voltage and current time-domain signals of an MMC under disturbance of multiple different voltage frequencies, obtaining output voltage and current frequency-domain data through fast Fourier analysis, determining equivalent impedance of the MMC of the network-forming flexible interconnection system at each frequency according to the output voltage and current frequency-domain data, and determining the equivalent impedance of the MMC of the network-forming flexible interconnection system according to the equivalent impedance. And taking the equivalent impedance and the working condition variable corresponding to each frequency as mapping samples, constructing a training data set, and training the initial fuzzy neural network, thereby enabling the trained MMC equivalent impedance prediction model to output an equivalent impedance prediction value of the MMC at the current calculation moment. Therefore, the impedance characteristics of the network-forming type MMC can be accurately represented in a wide working range.

The invention is suitable for the technical field of impedance calculation, and provides a new energy station impedance calculation method, which comprises the following steps: inputting acquired broadband impedance characteristic data into a preset clustering algorithm model for clustering analysis, and generating a plurality of unit clusters; calculating an equivalent impedance characteristic of the current cluster, and determining an equivalent frequency domain network equivalent FDNE unit corresponding to the current cluster according to the equivalent impedance characteristic; constructing a function taking maximization of a stability margin and minimization of a harmonic distortion rate as optimization targets, and solving an optimal solution set of the function by taking key parameters of each equivalent FDNE unit of the equivalent frequency domain network as optimization variables; according to the actual electrical topology of the new energy station, the optimized FDNE units are connected, and a full-field equivalent simulation model is constructed; calculating the equivalent impedance characteristic of the grid-connected point of the new energy station through a full-field equivalent simulation model; the calculation efficiency is greatly improved on the premise of ensuring the modeling precision.