196 results about "Impedance properties" patented technology

The invention relates to the technical field of GIS equipment, and discloses a partial discharge detection method and device for totally-enclosed vacuum environment-friendly GIS equipment, and the method comprises the steps: constructing a dual detection circuit system of the GIS equipment, and building an equipment impedance characteristic model which comprises housing distribution inductance and internal conductor distribution inductance; acquiring a first multi-mode discharge signal in a vacuum insulation environment, performing empirical mode decomposition to obtain a plurality of eigenmode function components, and synchronously recording environment characteristic parameters; constructing a discharge signal identification model; and identifying the second multi-mode discharge signal of the GIS equipment through the discharge signal identification model, and determining the internal defect three-dimensional coordinate and the hazard level of the GIS equipment, so that intelligent identification of discharge characteristics is realized, the calculation efficiency is improved, the anti-interference capability is enhanced, the three-dimensional coordinate of the internal defect of the GIS equipment can be accurately calculated, and the reliability of the GIS equipment is improved. And comprehensive evaluation of defect types and hazard levels is realized.

The invention provides an antenna radio frequency performance test system and method, and relates to the technical field of antenna testing, the system adopts an intelligent signal source module, uses a quantum random number generator to generate a test signal of an ultra-wide frequency spectrum, and an adaptive matching network module can automatically adjust impedance according to impedance characteristics of an antenna to be tested. The space electromagnetic environment reconstruction module accurately simulates various electromagnetic environments through an electromagnetic radiation source and a wave-absorbing material, the multi-dimensional signal acquisition module simultaneously acquires electric field, magnetic field, phase and frequency spectrum information, and the intelligent analysis and diagnosis module analyzes signal data by using an artificial intelligence algorithm and performs fault diagnosis based on a machine learning model. In general, the system and the method improve the comprehensiveness, the accuracy and the intelligentization of the antenna test, and provide a new test solution for the field of wireless communication.

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 discloses a direct current line pilot protection method and system based on a special frequency measurement impedance property, and the method comprises the steps: 1, calculating a wavelet transformation modulus maximum value of a line mode voltage through employing a wavelet transformation method, and starting protection when the wavelet transformation modulus maximum value meets a protection starting criterion; step 2, the rectification side protection unit and the inversion side protection unit calculate fault components of the line mode voltage and the line mode current in each data window; 3, calculating a real part and an imaginary part of the measured impedance under two specific frequencies; step 4, determining the fault direction by using the fault direction discrimination characteristic quantity and the fault direction criterion; step 5, when the fault directions determined by the rectification side protection unit and the inversion side protection unit are consistent, determining that an internal fault occurs, otherwise, determining that an external fault occurs, and returning to the step 1; and step 6, when the occurrence of the internal fault is judged, calculating a fault pole selection characteristic quantity, and judging a fault type and a fault line according to a fault pole selection criterion, thereby solving the problems that pilot protection is slow in action, high in synchronization requirement and influenced by distributed capacitance.

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 a new energy station multi-band oscillation risk online evaluation and early warning method and a storage medium, and the method comprises the steps: carrying out the frequency sweeping to obtain the frequency domain impedance characteristics of fans and photovoltaic equipment of various models in a new energy station under different typical working conditions, and carrying out the frequency sweeping to obtain the frequency domain impedance characteristics of a power grid under different typical working conditions; the power flow level of the new energy station and the power grid side is monitored online, the working condition types of a new energy unit and the power grid are judged according to online monitoring data, and a new energy station equivalent impedance model is established according to the impedance characteristics of fans and photovoltaic equipment of various models of the new energy station and the station topology. And on-line evaluation of oscillation risks is carried out based on the Nyquist criterion. And selecting whether to send an oscillation alarm signal based on the evaluation result. According to the method, the multi-band oscillation risk of the new energy station can be effectively evaluated and early warned, and safe and stable operation of the new energy station is ensured.

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 relates to a STATCOM impedance characteristic reconstruction method based on a real-time digital simulator, and belongs to the technical field of new energy electromagnetic transient simulation modeling. The method comprises the following steps: firstly, establishing a STATCOM single machine infinite bus system based on a real-time digital simulator; secondly, introducing voltage feed-forward control in a control link of the STATCOM to carry out impedance reconstruction, injecting a three-phase voltage disturbance signal into a body of the STATCOM when the STATCOM operates normally, and collecting three-phase voltage and current signals of a machine end of the STATCOM at the same time; and finally, the impedance characteristic of the STATCOM is calculated according to the collected voltage and current signals. According to the method, the impedance characteristic of the STATCOM is transformed, so that the negative damping characteristic of the STATCOM can be remarkably improved, and the oscillation risk of a power system is effectively reduced.

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 provides a broadband oscillation suppression method and device for a three-phase grid-connected inverter and a medium, and belongs to the field of new energy grid-connected broadband oscillation suppression. According to the impedance characteristic of the three-phase grid-connected inverter, a voltage feedback transfer function is designed, the transfer function is subjected to equivalence, complex coefficients in the transfer function are replaced, and the broadband oscillation suppression of the three-phase grid-connected inverter is achieved. And the method has definite physical significance and realizability. Meanwhile, a digital peak filter is introduced to serve as a frequency component selection channel, a delayer serves as a phase correction channel, a frequency component selection device only allowing a target frequency component to pass through is formed, a designed voltage feedback transfer function is combined, and a complete damping channel with a broadband oscillation suppression effect is formed. According to the channel, only the impedance characteristic of the target frequency can be changed, the impedance characteristic of the non-target frequency band is not influenced, the damping borrowing phenomenon is avoided, meanwhile, the coefficient can be changed according to the oscillation frequency, and full-band broadband oscillation can be suppressed.

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.

Systems and methods for sensing tissue in a phacoemulsification procedure are provided herein. A method may include generating a sensing signal through a frequency range centered at a local resonant frequency of an ultrasonic handpiece and measuring impedance characteristics of the signal at a distal end of a needle of an ultrasonic handpiece. A method may further include comparing the measured impedance characteristics of the generated sensing signal with one or more stored impedance profiles. A method may further include classifying, based on the comparison between the measured impedance characteristics and the stored one or more impedance profiles, a medium contacting the distal end of the needle. A method may further include controlling an output of the ultrasonic handpiece based on the classification of the medium contacting the tip of the needle.

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 relates to the technical field of power system modeling analysis, in particular to a frequency dependent impedance modeling method, device and equipment of a power transmission line and a medium. The method comprises the steps of obtaining resistance values and inductance values of a power transmission line at multiple frequency points, performing polynomial fitting on the resistance values and the inductance values at the multiple frequency points, and establishing an impedance model of the power transmission line based on an obtained frequency response fitting result of resistance and inductance of the power transmission line. Therefore, by comprehensively considering the distribution parameter characteristics and frequency correlation of the power transmission line, a model capable of accurately describing the impedance characteristics of the power transmission line under different frequencies is constructed, and the problem that the impedance characteristics of the power transmission line under different frequencies cannot be accurately described because only the distribution parameter characteristics of the power transmission line are simulated in the prior art is solved. The method solves the problem that limitation exists due to the fact that the frequency correlation of power transmission line parameters is not considered, improves the accuracy of power transmission line impedance modeling, and provides a theoretical basis for power system oscillation stability analysis.

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 high-voltage direct-current power transmission system oscillation suppression method based on MMC negative-sequence impedance remodeling. The method comprises the steps that equivalent admittance of a new energy unit considering MMC impedance characteristic influence is established; mMC negative sequence impedance remodeling control based on virtual parallel impedance is constructed; and designing control parameters considering impedance coupling degree constraint. According to the invention, the oscillation phenomenon of the system can be effectively suppressed, and safe and stable operation of the high-voltage direct-current power transmission system is ensured.

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 provides a circuit breaker closing resistor damage impedance characteristic simulation model construction method and device, and belongs to the technical field of circuit breaker closing resistor damage detection. Comprising the following steps: establishing a closing resistor string model based on geometric models of closing resistors in the circuit breaker; enabling a single closing resistor disc to be equivalent to a series-parallel connection form of a single RLC loop model, and building a distribution parameter model of the single closing resistor disc in the closing resistor model according to the damage type; constructing a circuit breaker closing resistor damage impedance characteristic simulation model according to a series-parallel connection relation between a closing resistor and a main port in the circuit breaker, and enabling a distribution parameter model of a single closing resistor disc to be equivalent to a lumped parameter model of each closing resistor disc in the circuit breaker closing resistor damage impedance characteristic simulation model through a vector matching method; and detecting the damage type and the actual damage condition of the closing resistor in an unknown circuit breaker by using the circuit breaker closing resistor damage impedance characteristic simulation model.

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.

According to an example embodiment, a method is provided, the method comprising: determining a respective impedance curve for a plurality of cells extracted from a plurality of rechargeable batteries, wherein each impedance curve is descriptive of an internal impedance of the respective cell as a function of frequency over a predefined frequency range; determining, for each of the plurality of cells, respective one or more impedance characteristics based on the impedance curve determined for the respective cell; and sorting the plurality of cells into one or more quality classes in accordance with the one or more impedance characteristics determined for the plurality of cells.

The invention relates to an STATCOM (Static Synchronous Compensator) broadband domain impedance characteristic acquisition method based on hardware-in-the-loop simulation. The method comprises the following steps: firstly, establishing an STATCOM single machine infinite bus system based on a hardware-in-the-loop simulation platform; then, when the STATCOM operates normally, a three-phase voltage disturbance signal with the amplitude being k% of the nominal voltage and the frequency being within the range of f1-f2 is injected into a body of the STATCOM, and meanwhile, three-phase voltage and current signals at the machine end of the STATCOM are collected; and finally, the broadband impedance of the system to be measured is calculated according to the collected voltage and current signals. According to the method, the impedance characteristic of the STATCOM in the range of f1-f2 can be accurately and quickly obtained, and the obtained result can provide an important basis for influence analysis of the STATCOM accessing a power grid.