A method, program, device and storage medium for obtaining system impedance by parallel injection disturbance

Abstract

This invention belongs to the field of power system technology, specifically relating to a method, program, device, and storage medium for obtaining system impedance through parallel disturbance injection. This invention can generate combined high- and low-frequency disturbance signals through composite disturbances, which can be directly used in the analysis and testing of system impedance. By supplying weakly coupled high- and low-frequency voltages to the power grid, the system impedance of multiple frequency bands can be analyzed simultaneously, effectively improving frequency sweep efficiency compared to traditional single-frequency methods. After injecting disturbances into the system under test, the obtained sampled data can be used to separate high-frequency and low-frequency disturbances and feedback signals from a single set of data, effectively shortening the total frequency sweep time and improving efficiency. This invention provides short disturbance durations for low-frequency and high-frequency systems, preventing the cumulative impact of continuous disturbances from the disturbance source on the system.

Description

Technical Field

[0001] This invention belongs to the field of power system technology, specifically relating to a method, program, device, and storage medium for obtaining system impedance by parallel injection of disturbances. Background Technology

[0002] Traditional power systems represent relatively stable loads and lines in terms of impedance. However, with power system upgrades, more and more power electronic devices are being connected to the grid. These devices exhibit impedance nonlinearity, thus placing higher demands on power system stability analysis and urgently requiring new methods and technologies to assist in analysis and provide a reference for subsequent system upgrades. This is especially true in scenarios such as ships and new energy power plants, where the increasing integration of power electronic devices with technological advancements places even greater demands on grid impedance acquisition techniques.

[0003] Traditional methods for power system impedance analysis include steady-state methods, dynamic methods, and numerical analysis methods. The small-signal disturbance analysis method under the dynamic method is usually used. This method involves injecting a specific disturbance frequency signal into the system under test, obtaining the corresponding frequency feedback signal at that frequency through FFT decomposition, and finally drawing the impedance Bode plot of the current power grid under test.

[0004] For small-signal perturbation analysis, there are related optimization methods (CN202311406609 - A broadband oscillation electromagnetic simulation analysis method and system for photovoltaic access systems), and there are also improvements in the modeling method (CN202410589064 - A conventional DC impedance modeling method based on multi-harmonic linearization). The purpose is to improve the accuracy of modeling and avoid oscillations in the theoretical modeling stage.

[0005] Traditional small-signal disturbance analysis methods involve injecting a single-frequency disturbance within a fixed period. This method can obtain the impedance at the corresponding frequency. However, since the frequency sweeping process actually requires a large number of frequencies, the sweeping time is longer. Moreover, the longer the sweeping process lasts, the more harmonics of different frequencies accumulated in the power grid, posing potential risks and affecting the results of sweeping other frequencies. Summary of the Invention

[0006] The purpose of this invention is to provide a method, program, device, and storage medium for obtaining system impedance by parallel injection of perturbations.

[0007] A method for obtaining system impedance through parallel perturbation injection includes the following steps:

[0008] Step 1: Combine and modulate the low-frequency signal with the high-frequency signal to generate a combined perturbation signal; generate an intermediate-frequency perturbation signal independently from the intermediate-frequency signal; and continuously splice the combined perturbation signal and the intermediate-frequency perturbation signal to form a sweep signal with a complete sweep cycle.

[0009] Step 2: The swept frequency signal is used as a reference signal and passed to the disturbance source. The disturbance source generates a disturbance signal that is consistent with the reference signal and injects the disturbance signal into the system under test.

[0010] Step 3: Collect the input signal and feedback output signal of the disturbance source connected to the node of the system under test; filter the collected signals to separate the high-frequency input and output signals and the low-frequency input and output signals, and calculate the high-frequency impedance and low-frequency impedance respectively through Fourier decomposition.

[0011] Furthermore, in step 1, the low-frequency signal and the high-frequency signal are synthesized and modulated, specifically as follows:

[0012]

[0013] Where A1 is the amplitude of the high-frequency signal, and f1 is the frequency of the high-frequency signal. A1 represents the initial phase of the high-frequency signal; A2 represents the amplitude of the low-frequency signal; and f2 represents the frequency of the low-frequency signal. t1 represents the initial phase of the low-frequency signal; t2 represents the total duration required for the aliased signal. f Lmin f represents the minimum frequency of a low-frequency signal and the maximum frequency of a high-frequency signal. Hmax The minimum value f that a high-frequency signal can sweep to. Hmin The sweep step size Δf of high-frequency signals H The maximum frequency f of low-frequency signals Lmax With minimum frequency f Lmin satisfy:

[0014] Furthermore, in step 1, the intermediate frequency signal is used to independently generate an intermediate frequency perturbation signal, specifically as follows:

[0015]

[0016] Where A3 is the amplitude of the mid-frequency signal, and f3 is the frequency of the mid-frequency signal. t1 represents the initial phase of the mid-frequency signal; t2 represents the duration of the mid-frequency disturbance signal. f Mmax f is the maximum frequency of the mid-frequency disturbance signal. Mmin Δf is the minimum frequency of the mid-frequency disturbance signal. M This represents the sweep step size for the mid-frequency band signal.

[0017] Furthermore, in step 3, a Butterworth filter is used to filter the acquired signal. Low-frequency and high-frequency signals are preprocessed by the Butterworth filter, while mid-frequency signals are directly used without preprocessing.

[0018] Furthermore, the Butterworth bandstop filter is designed to have passband and stopband boundary frequencies that are symmetrical about the center frequency, and calibration is performed through the following steps:

[0019] Step 3.1: Calculate the passband center frequency;

[0020]

[0021] in, f s This refers to the sampling frequency inside the sampling instrument;

[0022] Step 3.2: Calculate the passband boundary frequency;

[0023]

[0024] Step 3.3: Check if the passband boundary frequency satisfies symmetry; if ω p1 '=ω p2 If the passband boundary frequency is symmetrical, no adjustment is needed; otherwise, adjust the passband boundary frequency.

[0025] Step 3.4: Calculate the stopband center frequency;

[0026]

[0027] Step 3.5: Calculate the stopband boundary frequency;

[0028]

[0029] Step 3.6: Check if the stopband boundary frequency satisfies symmetry; if ω s1 '=ω s2 If the stopband boundary frequency is symmetrical, no adjustment is needed; otherwise, adjust the stopband boundary frequency.

[0030] Step 3.7: Determine the z-domain transfer function of the Butterworth band-stop filter, expand the z-domain transfer function, find the poles and zeros, and decompose the z-domain transfer function into several second-order filter segments through difference equations.

[0031]

[0032] Where, ω c Where is the edge cutoff frequency, and N is the order of the Butterworth band-stop filter.

[0033] Furthermore, in step 3, the filtered signal is first segmented, and the input disturbance frequency is found between the nth second and the (n+m)th second. After determining the disturbance, the m-second signal is subjected to Fourier decomposition to extract the voltage and current corresponding to the input disturbance frequency. Then, the impedance is calculated. The calculation process is as follows:

[0034]

[0035] Where, U(f) i and I(f) i Let Z(f) represent the voltage and current signals generated when the i-th disturbance frequency occurs, respectively. i This represents the impedance corresponding to each frequency in a complete sweep cycle at the current disturbance frequency. The impedance is in complex form. Calculate the magnitude and phase angle of the impedance:

[0036]

[0037] Among them, Mag i Let Z(f)i represent the magnitude of the i-th impedance, Phase i The phase angle represents the impedance Z(f)i.

[0038] A computer device / apparatus / system includes a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method for obtaining system impedance by parallel injection of perturbations described above.

[0039] A computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implements the steps of the method for obtaining system impedance by parallel injection of perturbations described above.

[0040] A computer program product includes a computer program / instructions that, when executed by a processor, implement the steps of the method for obtaining system impedance by parallel injection of perturbations described above.

[0041] The beneficial effects of this invention are as follows:

[0042] This invention generates combined high- and low-frequency disturbance signals through composite perturbation, which can be directly used in the analysis and testing of system impedance. By supplying weakly coupled high- and low-frequency voltages to the power grid, this invention can simultaneously analyze the system impedance of multiple frequency bands, effectively improving frequency sweep efficiency compared to traditional single-frequency methods. After injecting disturbances into the system under test, the obtained sampled data can be used to separate high-frequency and low-frequency disturbances and feedback signals from a single data set, effectively shortening the total frequency sweep time and improving efficiency. This invention also features short disturbance durations for low- and high-frequency systems, preventing the cumulative impact of continuous disturbances from the disturbance source on the system. Attached Figure Description

[0043] Figure 1 A flowchart for injecting disturbances into the system under test.

[0044] Figure 2 The diagram serves as a verification tool for both theoretical modeling and simulation modeling.

[0045] Figure 3 This is a schematic diagram of the disturbance source model.

[0046] Figure 4 This is a schematic diagram of the high-frequency and low-frequency aliasing cycle.

[0047] Figure 5 This is a schematic diagram of signal acquisition.

[0048] Figure 6 The present invention provides an overall flowchart of a method for obtaining system impedance through parallel injection of perturbations. Detailed Implementation

[0049] The present invention will now be further described with reference to the accompanying drawings.

[0050] Traditional small-signal disturbance analysis methods involve simultaneously injecting a single-frequency disturbance signal into the power grid. This invention, however, injects both high-frequency and low-frequency signals in parallel. By decoupling the input and feedback disturbances in these two frequency bands, the impedance corresponding to each frequency can be obtained. Using a frequency sweep with two injected frequencies for impedance analysis effectively shortens the sweep time. Reduced sweep time minimizes the impact of small-signal accumulation on the system. Parallel frequency sweeping exhibits weak coupling between low and high frequencies, allowing for direct filtering of voltages and currents at each frequency during data processing. This results in a simple and efficient signal processing method.

[0051] A method for obtaining system impedance through parallel perturbation injection includes the following steps:

[0052] Step 1: Combine and modulate the low-frequency signal with the high-frequency signal to generate a combined perturbation signal; generate an intermediate-frequency perturbation signal independently from the intermediate-frequency signal; and continuously splice the combined perturbation signal and the intermediate-frequency perturbation signal to form a sweep signal with a complete sweep cycle.

[0053] The low-frequency signal is synthesized and modulated with the high-frequency signal, specifically as follows:

[0054]

[0055] Where A1 is the amplitude of the high-frequency signal, and f1 is the frequency of the high-frequency signal. A1 represents the initial phase of the high-frequency signal; A2 represents the amplitude of the low-frequency signal; and f2 represents the frequency of the low-frequency signal. t1 represents the initial phase of the low-frequency signal; t2 represents the total duration required for the aliased signal. f Lmin f represents the minimum frequency of a low-frequency signal and the maximum frequency of a high-frequency signal. Hmax The minimum value f that a high-frequency signal can sweep to. Hmin The sweep step size Δf of high-frequency signals H The maximum frequency f of low-frequency signals Lmax With minimum frequency f Lmin satisfy:

[0056] The intermediate frequency signal is used to generate an independent intermediate frequency perturbation signal, specifically as follows:

[0057]

[0058] Where A3 is the amplitude of the mid-frequency signal, and f3 is the frequency of the mid-frequency signal. t1 represents the initial phase of the mid-frequency signal; t2 represents the duration of the mid-frequency disturbance signal. f Mmax f is the maximum frequency of the mid-frequency disturbance signal. Mmin Δf is the minimum frequency of the mid-frequency disturbance signal. M This is the sweep step size for the mid-frequency band signal;

[0059] Step 2: The swept frequency signal is used as a reference signal and passed to the disturbance source. The disturbance source generates a disturbance signal that is consistent with the reference signal and injects the disturbance signal into the system under test.

[0060] Step 3: Collect the input signal and feedback output signal of the disturbance source connected to the node of the system under test; filter the collected signals to separate the high-frequency input and output signals and the low-frequency input and output signals, and calculate the high-frequency impedance and low-frequency impedance respectively through Fourier decomposition.

[0061] The acquired signals are filtered using a Butterworth filter. Low-frequency and high-frequency signals are preprocessed using the Butterworth filter, while mid-frequency signals are used directly without preprocessing.

[0062] The design of a Butterworth bandstop filter requires that the passband and stopband boundary frequencies be symmetrical about the center frequency. Calibration is performed using the following steps:

[0063] Step 3.1: Calculate the passband center frequency;

[0064]

[0065] in, f s This refers to the sampling frequency inside the sampling instrument;

[0066] Step 3.2: Calculate the passband boundary frequency;

[0067]

[0068] Step 3.3: Check if the passband boundary frequency satisfies symmetry; if ω p1 '=ω p2 If the passband boundary frequency is symmetrical, no adjustment is needed; otherwise, adjust the passband boundary frequency.

[0069] Step 3.4: Calculate the stopband center frequency;

[0070]

[0071] Step 3.5: Calculate the stopband boundary frequency;

[0072]

[0073] Step 3.6: Check if the stopband boundary frequency satisfies symmetry; if ω s1 '=ω s2 If the stopband boundary frequency is symmetrical, no adjustment is needed; otherwise, adjust the stopband boundary frequency.

[0074] Step 3.7: Determine the z-domain transfer function of the Butterworth band-stop filter, expand the z-domain transfer function, find the poles and zeros, and decompose the z-domain transfer function into several second-order filter segments through difference equations.

[0075]

[0076] Where, ω c Where is the edge cutoff frequency, and N is the order of the Butterworth band-stop filter.

[0077] The filtered signal is first segmented, and the input perturbation frequency is found between the nth second and the n+mth second. After identifying the perturbation, the m-second signal is subjected to Fourier decomposition to extract the voltage and current corresponding to the input perturbation frequency. Then, the impedance is calculated. The calculation process is as follows:

[0078]

[0079] Where, U(f) i and I(f) i Let Z(f) represent the voltage and current signals generated when the i-th disturbance frequency occurs, respectively. i This represents the impedance corresponding to each frequency in a complete sweep cycle at the current disturbance frequency. The impedance is in complex form. Calculate the magnitude and phase angle of the impedance:

[0080]

[0081] Among them, Mag i Let Z(f)i represent the magnitude of the i-th impedance, Phase i The phase angle represents the impedance Z(f)i.

[0082] Example 1:

[0083] For power systems with a power frequency of 50 / 60Hz, the disturbance frequencies are divided into a low-frequency band of 1-10Hz, a mid-frequency band of 10Hz-100Hz, and a high-frequency band above 100Hz. Because mid-frequency parameters and system coupling are prone to coupling with the power frequency, it is usually necessary to avoid aliasing between mid-frequency and power frequency signals during frequency sweeping. Therefore, during parallel frequency sweeping, the low-frequency and high-frequency signals are synthesized and modulated. In addition to the synthesized modulation signal, the mid-frequency signal independently generates a reference signal. The reference signal and the synthesized signal are continuously spliced ​​together to form a complete sweep signal for a sweep cycle. This sweep signal is used as a reference and passed to the disturbance source. The disturbance source generates a disturbance signal consistent with the reference wave, and the generated disturbance is injected into the system under test. The system disturbance flowchart is as follows: Figure 1 As shown.

[0084] The input and feedback output signals of the disturbance source access node are collected and recorded using instruments. The collected signals are separated into high-frequency and low-frequency input / output signals. Parameters for their respective frequencies are calculated based on the input and output signals: when the disturbance input is voltage and the feedback is current, the calculated parameter is the system conductance; when the disturbance input is current and the feedback is voltage, the calculated parameter is the system impedance. All calculated parameters are plotted on a Bode plot using calculation software. The theoretical Bode plot and the actual Bode plot are compared to ensure consistency between the theoretical model and the actual model.

[0085] 1. Theoretical calculation method for system parameters:

[0086] The system requires the calculation of impedance or admittance parameters. Specific impedance modeling methods are used to analyze these parameters, including dq impedance modeling, positive and negative sequence impedance modeling, or harmonic linearization, to perform equivalent modeling of all devices in the system and construct an overall theoretical model.

[0087]

[0088] 2. Simulation model construction:

[0089] In simulation software such as MATLAB and Plescs, simulation models and mathematical models with parameters completely consistent with theoretical modeling are established, such as... Figure 2 As shown.

[0090] 3. Establish a disturbance source model:

[0091] In the Matlab environment, create a controlled voltage source or a controlled current source, connect the controlled source to the node under test, and ensure the controlled interface is well-designed to support the generation of disturbance reference waveforms, such as... Figure 3 As shown.

[0092] 4. Design a perturbation generation algorithm:

[0093] Given a low-frequency generation function, the logic and control algorithm for generating both high-frequency and low-frequency signals are designed simultaneously for the low-frequency band of 1Hz-10Hz and the high-frequency band above 100Hz. These signals are then superimposed to form a disturbance signal, which is then applied to the established controlled source. The function is tested in an environment. The specific calculation method for the disturbance source generation function is as follows:

[0094]

[0095] After completing the high and low frequency disturbance signal synthesis and frequency sweep, it is also necessary to set the disturbance source at the intermediate frequency. The disturbance function in the intermediate frequency band is as follows:

[0096]

[0097] 5. Set the frequency sweep rule sequence:

[0098] After completing the preparations in steps 1-4, the parameters for setting the frequency sweep include:

[0099] ① Disturbance frequency;

[0100] ② Duration of the disturbance;

[0101] When performing a full-cycle frequency sweep, the system requires a longer time and period in the low-frequency sweep interval. Therefore, based on the time required for the low-frequency cycle, multiple high-frequency cycles are mixed into one low-frequency cycle. Frequency segmentation is typically divided into three frequency bands, with the frequency intervals as follows:

[0102] ① Low frequency: 0.1-10Hz

[0103] ②Medium frequency: 10-100Hz

[0104] ③ High frequency: above 100Hz

[0105] The relationship between the generation period and the high-frequency period is as follows:

[0106]

[0107] In the formula, f Hmax f is the maximum frequency value in the high-frequency band. Hmin Δf is the minimum value that can be swept to the high-frequency band. H f is the sweep step size for the high-frequency band.Lmax f is the maximum frequency in the low-frequency band. Lmin t1 is the minimum frequency in the low-frequency band. t1 is the total duration required for the aliasing signal.

[0108] Taking a 1Hz period as an example, in the first 1 second, in addition to the 1Hz low-frequency disturbance, 10 high-frequency signals with a duration of 0.1s can also be superimposed. The relationship between frequency and time is shown in the attached figure. Figure 4 As shown.

[0109] Typically, low and high frequencies are scanned at a fixed period of 0.1s, with a high-frequency step size of 10Hz. This means that within 10 seconds of the entire low-frequency sweep, a high-frequency band scan from 100Hz to 1000Hz can be performed simultaneously. The high-frequency step size can also be changed; for example, setting the high-frequency band step size to 20Hz will enable a scan from 100Hz to 1900Hz.

[0110] The total sweep time for the mid-frequency band is:

[0111]

[0112] The time required for traditional frequency sweep is t L +t M +t H This method can achieve a total duration of t1+t2, which can greatly reduce the total duration.

[0113] 5. Real-world verification:

[0114] In practical applications, the disturbance characteristics mentioned in this embodiment are used as a disturbance source reference signal source connected to the power grid under test. A disturbance signal is injected into the power grid, and the system's input and feedback signals are measured and recorded using specialized instruments. Figure 5 As shown.

[0115] 6. Signal Acquisition and Processing:

[0116] Since the data acquired after frequency sweeping has no real-time requirements, preprocessing of the composite modulated high-frequency and low-frequency signals can be performed using a Butterworth filter. Intermediate-frequency (IF) signals can be directly used without preprocessing, and the sampled signals can also be directly used. The system then performs data conversion and processing on the sampled data, and finally uses a filtering algorithm to extract the high-frequency and low-frequency signal waveforms. Signals in the IF band can be processed directly without a filter. The processing flow is as follows:

[0117] (1) Define requirements and technical specifications

[0118] The following technical specifications are specified:

[0119] Passband boundary frequency: f Lmax fHmin ;

[0120] Stopband boundary frequency: f Lmax +Δf M f Hmin -Δf M ;

[0121] Maximum passband attenuation: A p ;

[0122] Minimum stopband attenuation: A s ;

[0123] Sampling frequency: determined by the internal sampling frequency (f) of the sampling instrument. s )Decide;

[0124] These metrics will serve as requirements to ensure that the filter meets the necessary specifications.

[0125] (2) Standardized frequency calculation

[0126] These frequency parameters are converted to standard frequencies relative to the Nyquist frequency.

[0127] Nyquist frequency:

[0128] Normalized passband boundary frequency:

[0129] Standardized stopband boundary frequency:

[0130] (3) Geometric symmetry calibration

[0131] The design of a Butterworth bandstop filter requires that the passband and stopband boundary frequencies be symmetrical about the center frequency. Calibration is performed using the following steps:

[0132] 1) Calculate the passband center frequency:

[0133] 2) Calculate the new passband boundary frequency:

[0134] 3) Check if symmetry is satisfied: when ω p1 '=ω p2 When the passband is symmetrical, no adjustment is needed.

[0135] Symmetry is also required at the stopband boundary frequencies, which means they should also satisfy similar conditions:

[0136] 1) Calculate the stopband center frequency:

[0137] 2.) Check for symmetry:

[0138] 3.) Adjust the stopband boundary frequency: when ω s1 '=ω s2 When the passband is symmetrical, no adjustment is needed. When it is not symmetrical, adjust the boundary frequency.

[0139] (4) Determine the filter function

[0140] The transfer function of the Basswater filter is in the form of:

[0141]

[0142] In the formula, ω c Here, is the edge cutoff frequency, and N is the filter order. In offline processing, a higher order can be used to obtain better filtering characteristics. To transform the transfer function in the s-domain to the z-domain for implementation in the digital domain, we use a bilinear transform:

[0143]

[0144] Where T is the sampling period, Replacing 's' yields the final z-domain transfer function.

[0145] (5) Implementing digital filters

[0146] With the z-domain transfer function, we can decompose it into several second-order filter segments and implement the filters by calculating the poles and zeros. We expand the z-domain transfer function, find the poles and zeros, and then implement each filter segment using difference equations.

[0147] 7. Data Consistency Verification

[0148] After filtering, the signal is separated into three frequency bands and decomposed using FFT to obtain the impedance corresponding to each frequency throughout the system's cycle. The amplitude and phase angle are then calculated, and the results of all frequencies obtained from the frequency sweep are plotted on a Bode plot to obtain the final impedance fast sweep result. This result, along with the previously performed theoretical modeling result, is plotted on the same Bode plot using software. Consistency verification increases the reliability. Based on the sampled data, this invention effectively improves the information density of the data; a single set of multi-frequency perturbation data can yield two sets of impedances, effectively improving data utilization.

[0149] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for obtaining system impedance through parallel perturbation injection, characterized in that, Includes the following steps: Step 1: Combine and modulate the low-frequency signal with the high-frequency signal to generate a combined perturbation signal; generate an intermediate-frequency perturbation signal independently from the intermediate-frequency signal; and continuously splice the combined perturbation signal and the intermediate-frequency perturbation signal to form a sweep signal with a complete sweep cycle. The specific steps of combining and modulating low-frequency signals with high-frequency signals are as follows: Where A1 is the amplitude of the high-frequency signal, and f1 is the frequency of the high-frequency signal. A1 represents the initial phase of the high-frequency signal; A2 represents the amplitude of the low-frequency signal; and f2 represents the frequency of the low-frequency signal. t1 represents the initial phase of the low-frequency signal; t2 represents the total duration required for the aliased signal. f Lmin f represents the minimum frequency of a low-frequency signal and the maximum frequency of a high-frequency signal. Hmax The minimum value f that a high-frequency signal can sweep to. Hmin The sweep step size Δf of high-frequency signals H The maximum frequency f of low-frequency signals Lmax With minimum frequency f Lmin satisfy: Step 2: The swept frequency signal is used as a reference signal and passed to the disturbance source. The disturbance source generates a disturbance signal that is consistent with the reference signal and injects the disturbance signal into the system under test. Step 3: Collect the input signal and feedback output signal of the disturbance source connected to the node of the system under test; filter the collected signals to separate the high-frequency input and output signals and the low-frequency input and output signals, and calculate the high-frequency impedance and low-frequency impedance respectively through Fourier decomposition.

2. The method for obtaining system impedance by parallel injection of perturbations according to claim 1, characterized in that: In step 1, the intermediate frequency signal is used to independently generate an intermediate frequency disturbance signal, specifically as follows: Where A3 is the amplitude of the mid-frequency signal, and f3 is the frequency of the mid-frequency signal. t1 represents the initial phase of the mid-frequency signal; t2 represents the duration of the mid-frequency disturbance signal. f Mmax f is the maximum frequency of the mid-frequency disturbance signal. Mmin Δf is the minimum frequency of the mid-frequency disturbance signal. M This is the sweep step size for the mid-frequency band signal.

3. The method for obtaining system impedance by parallel injection of perturbations according to claim 2, characterized in that: In step 3, a Butterworth filter is used to filter the acquired signal. Low-frequency and high-frequency signals are preprocessed by the Butterworth filter, while mid-frequency signals are directly used without preprocessing.

4. The method for obtaining system impedance by parallel injection of perturbations according to claim 3, characterized in that: The Butterworth bandstop filter is designed to have symmetrical passband and stopband boundary frequencies about the center frequency. Calibration is performed using the following steps: Step 3.1: Calculate the passband center frequency; in, f s This refers to the sampling frequency inside the sampling instrument; Step 3.2: Calculate the passband boundary frequency; Step 3.3: Check if the passband boundary frequency satisfies symmetry; if ω p1 '=ω p2 If the passband boundary frequency is symmetrical, no adjustment is needed; otherwise, adjust the passband boundary frequency. Step 3.4: Calculate the stopband center frequency; Step 3.5: Calculate the stopband boundary frequency; Step 3.6: Check if the stopband boundary frequency satisfies symmetry; if ω s1 '=ω s2 If the stopband boundary frequency is symmetrical, no adjustment is needed; otherwise, adjust the stopband boundary frequency. Step 3.7: Determine the z-domain transfer function of the Butterworth band-stop filter, expand the z-domain transfer function, find the poles and zeros, and decompose the z-domain transfer function into several second-order filter segments through difference equations. Where, ω c Where is the edge cutoff frequency, and N is the order of the Butterworth band-stop filter.

5. The method for obtaining system impedance by parallel injection of perturbations according to claim 4, characterized in that: In step 3, the filtered signal is first segmented. From the nth second to the n+mth second, the input disturbance frequency is found. After determining the disturbance, the m-second signal is subjected to Fourier decomposition to extract the voltage and current corresponding to the input disturbance frequency. Then, the impedance is calculated. The calculation process is as follows: Where, U(f) i and I(f) i Let Z(f) represent the voltage and current signals generated when the i-th disturbance frequency occurs, respectively. i This represents the impedance corresponding to each frequency in a complete sweep cycle at the current disturbance frequency. The impedance is in complex form. Calculate the magnitude and phase angle of the impedance: Among them, Mag i Let Z(f) represent the i-th impedance. i Amplitude, Phase i Represents the impedance Z(f) i The phase angle.

6. A computer device / equipment / system, comprising a memory, a processor, and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program / instructions stored thereon, characterized in that: When the computer program / instructions are executed by the processor, they implement the steps of the method according to any one of claims 1 to 5.

8. A computer program product comprising a computer program / instructions, characterized in that: When the computer program / instructions are executed by the processor, they implement the steps of the method according to any one of claims 1 to 5.

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