163 results about "Impedance properties" patented technology

The invention discloses a virtual synchronous machine control-based impedance modeling and virtual impedance design method for a network construction type MMC (Modular Multilevel Converter). The method comprises the following steps: firstly, establishing a mathematical model of a network construction type MMC converter based on virtual synchronous machine control through a control strategy, and establishing a sequence impedance model of the MMC by adopting a harmonic linearization method; secondly, designing virtual impedance control to optimize traditional VSG control, and proposing a sequence impedance model after introduction of the virtual impedance control; and finally, analyzing impedance characteristics and grid-connected stability of the MMC converter after virtual impedance control is introduced. According to the method, the MMC sequence impedance model based on virtual impedance control can be effectively established, the grid-connected stability of the MMC sequence impedance model is analyzed, and the method has economical and practical values.

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 present invention belongs to the field of mechanical engineering, and particularly relates to an equivalent model of a knocking kinematic pair of a continuous elastic body and a modeling method thereof. An equivalent model is established for the knocking kinematic pair in a continuous elastic body mechanical structure or system, that is, the non-linear mapping relationship between the knocking pulse force and the knocking initial velocity. By assuming that the knocking force pulse is a half-cycle sine wave, and simultaneously using the Hertz contact model and the origin transfer function or impulse response function of the mechanical structure at the knocking contact point to express the contact mechanical properties of the knocking pair material pair and the impedance properties of the mechanical structure at the knocking part, the relationship between the output and input of the non-linear equivalent model, that is, the knocking pulse force and the knocking initial velocity, is derived. Through the method of the present invention, the problem of rapid prediction of the knocking force pulse of a continuous elastic body mechanical structure can be solved.

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 belongs to the technical field of noise source impedance extraction, and discloses a noise source impedance extraction optimization method and system considering the sensitivity of an insertion loss method, and the method comprises the steps: extracting an equivalent circuit of noise source impedance based on the insertion loss method, and calculating a noise attenuation coefficient through the equivalent circuit, a noise source impedance amplitude and phase information are sought according to the noise attenuation coefficient; calculating relative sensitivity by using the noise source impedance amplitude and phase information, and analyzing an influence rule of a noise attenuation coefficient on noise source impedance extraction precision based on the relative sensitivity; and generating a setting rule of a noise attenuation coefficient according to the influence rule, extracting a frequency band meeting the noise source impedance requirement by using the setting rule, and determining the inductance to perform noise source impedance extraction optimization operation. According to the method, firstly, analytical expressions of noise source impedance amplitude and phase are deduced, the influence rule of the noise source impedance property on noise source impedance extraction precision is analyzed, and the requirement required to be met by noise source impedance extraction precision is improved.

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 high-frequency transformer high-frequency oscillation analysis method and system considering stray parameters of a power supply line under high-frequency square wave excitation. According to the method, an open-circuit and short-circuit test means is adopted to obtain impedance parameters of the high-frequency transformer, and distribution parameters such as power supply line resistance, parasitic inductance and parasitic capacitance of the high-frequency transformer are obtained through impedance characteristic test. On this basis, a distribution parameter model of the high-frequency transformer is constructed, and order reduction splitting is performed on the distribution parameter model on the premise of neglecting capacitance between windings, so that a low-order sub-circuit model easy to analyze is formed. And the equivalent distribution parameter sub-circuit model obtained through reduced-order splitting is utilized to analyze and calculate the response of the transformer port voltage and the winding current under high-frequency square wave excitation, and detailed analysis of the waveform of the high-frequency transformer and research of the high-frequency oscillation characteristic are realized. The method can quantify the specific influence of the parameters of the high-frequency transformer on the oscillation characteristics, provides guidance for the suppression and elimination of high-frequency oscillation, and guarantees the efficient and stable operation of the high-frequency transformer.

The invention discloses a new energy station impedance identification method, system and device based on data driving and a storage medium. The method comprises the steps that two sets of independent disturbance signals are designed; respectively injecting two groups of disturbance signals into each single-machine grid-connected point, respectively measuring voltage and current signals of the single-machine grid-connected point under an abc coordinate system, and converting the voltage and current signals into voltage and current signals of the single-machine grid-connected point under a dq axis; single-machine grid-connected point impedance under the dq axis is calculated, and impedance data of all single-machine grid-connected points are obtained; dividing all impedance data and all voltage and current signals under the dq axis; initializing the ANN model to obtain a basic ANN model; and training and evaluating the basic ANN model, adjusting the basic ANN model according to an evaluation result, and finally outputting an ANN-based impedance identification model. According to the method, internal control parameters of the converter are not needed, the impedance characteristic can be updated online, and the new energy station impedance based on the voltage source converter can be identified under wide operating points.

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 discloses a power grid simulator control method based on generalized second-order differential simulation impedance characteristics, belongs to the technical field of power grid simulator control, and is suitable for a line impedance characteristic simulation system. The control method comprises the steps of firstly calculating active power and reactive power of a power grid simulator, then calculating through a VSG algorithm to obtain an output voltage instruction, and finally adding a virtual complex impedance based on generalized second-order differential on the basis of an original voltage and current double-closed-loop feedback control system to realize a simulation function of system line impedance. The generalized second-order differential function keeps the phase lead compensation differential effect on a specific frequency range, and eliminates the inherent high-frequency noise amplification effect of a traditional differential function. According to the control method, the dynamic performance of the system can be effectively improved, the output signal ripple is small, and the control speed is high.

The invention discloses a harmonic suppression method based on virtual impedance cooperative control, relates to the technical field of power grid harmonic control, and is used for solving the technical problems of high harmonic time variation, high treatment energy consumption and parameter solidification in a high-permeability photovoltaic scene. The method comprises the following steps: acquiring an original electric signal and an impedance parameter of a power grid side and a filtering parameter of an inverter side; performing real-time phase correction according to the original electric signal to obtain a multi-band harmonic frequency; virtual impedance is constructed based on the multi-band harmonic frequency, and an impedance characteristic matrix is generated based on the impedance parameters and the filtering parameters; performing parameter optimization based on deep reinforcement learning on the virtual impedance by adopting the impedance characteristic matrix to obtain an optimal virtual impedance parameter; and changing the equivalent output impedance of the inverter through the virtual impedance under the optimal virtual impedance parameter so as to realize harmonic suppression.

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 a wire harness radiation simulation method and system based on magnetic ring impedance frequency response characteristics. Measurement points are selected around an electromagnetic simulation coupling model about a magnetic ring, a wire harness and a metal structure around the wire harness; the excitation condition data and the impedance characteristic notepad document of the magnetic ring are input for simulation analysis, a curve chart of the first electric field radiation value of the measuring point changing along with the frequency is obtained, the magnetic ring does not need to be arranged on the whole vehicle for actual verification in the process, and the impedance frequency response characteristic curve of the magnetic ring is converted into the impedance characteristic notepad document; obtaining the electric field radiation values of the measuring points under different frequencies after the magnetic ring of the specification type is arranged; in addition, simulation can be carried out again after the specification and the installation position of the magnetic ring are modified, so that the specification and the installation position of the magnetic ring meeting requirements are quickly determined, and the test time is shortened; results of simulation analysis provide references for modification and adjustment of specifications and installation positions, so that modification randomness is avoided, and certain guidance is provided for direct-current fast-charging wire harness electromagnetic radiation standard-exceeding rectification.

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 present invention discloses a power impedance modeling method based on virtual synchronous control, which performs dq impedance modeling for port shore power supply in frequency bands based on virtual synchronous control, including: respectively constructing each small-signal dq model required for dq impedance modeling; according to the constructed small-signal dq models, using different dynamic links for modeling in different frequency bands, where in the low-frequency region, the dynamic links used are the power controller and the voltage controller; in the medium-low frequency region, the dynamic links used are the voltage-current loop and the power loop; in the intermediate frequency region, the dynamic link used is the voltage-current loop; in the high-frequency region, the dynamic links used are the current loop, the sampling low-pass filter, the control delay, and the voltage loop. The present invention can accurately characterize the differences in impedance characteristics of port shore power supply in each frequency band, construct an accurate impedance model based on virtual synchronous control in frequency bands, and effectively realize the small-signal stability assessment of the port shore power supply system.

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.