Method for acquiring system impedance through parallel injection disturbance, program, equipment and storage medium

Abstract

The invention belongs to the technical field of power systems, and particularly relates to a method for acquiring system impedance through parallel injection disturbance, a program, equipment and a storage medium. According to the invention, a high-low frequency combined disturbance signal can be generated in a composite disturbance mode, and the signal can be directly used in analysis and test of system impedance; by transmitting weakly coupled high-low frequency band voltage to a power grid, multi-frequency band system impedance can be analyzed at the same time, and the frequency sweeping efficiency can be effectively improved compared with a traditional single frequency; after disturbance is injected into the to-be-tested system, high-frequency and low-frequency disturbance and feedback signals can be separated from a group of data according to the obtained sampling data, so that the total frequency sweeping time can be effectively shortened, and the frequency sweeping efficiency is improved. According to the invention, the disturbance duration of low-frequency and high-frequency systems is short, and the accumulated influence of continuous disturbance of a disturbance source on the system is prevented.

Description

Technical Field

[0001] The present invention belongs to the technical field of power systems, and in particular relates to a method, a program, a device and a storage medium for obtaining system impedance by injecting disturbances in parallel. Background Art

[0002] The impedance state of the traditional power system is relatively stable load and line. With the upgrade of the power system, more and more power electronic devices are connected to the grid. Such equipment shows the characteristics of impedance nonlinearity, so higher requirements are put forward for the stability analysis of the power system, and new methods and technologies are urgently needed to realize auxiliary analysis to provide reference for the subsequent upgrade and transformation of the system. In particular, with the increase in scenes such as ships and new energy stations, with the upgrade of technology, more and more power electronic devices are connected to the site, which puts forward more requirements for the acquisition technology of grid impedance.

[0003] Traditional power system impedance analysis methods include steady-state method, dynamic method, and numerical analysis method. The small signal perturbation analysis method under the dynamic method is usually used. This method injects a specific disturbance frequency signal into the system to be tested, and then obtains the corresponding frequency feedback signal at this frequency through FFT decomposition, and finally draws the impedance Bode diagram of the current power grid to be tested.

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

[0005] The characteristic of the traditional small signal perturbation analysis method is to inject a single frequency disturbance within a fixed period. This method can achieve the acquisition of the impedance of the corresponding frequency. However, since there are many frequencies that need to be swept in the frequency sweep, the frequency sweep takes a longer time. In addition, the longer the frequency sweep lasts, the more harmonics of different frequencies accumulated in the power grid, which has potential risks and affects the results of other frequency sweeps. Summary of the invention

[0006] The object of the present invention is to provide a method, program, device and storage medium for obtaining system impedance by parallel injection disturbance.

[0007] A method for obtaining system impedance by parallel injection disturbances comprises the following steps:

[0008] Step 1: synthesize and modulate the low-frequency band signal and the high-frequency band signal to generate a synthesized disturbance signal; independently generate an intermediate-frequency band disturbance signal from the intermediate-frequency band signal; and continuously splice the synthesized disturbance signal and the intermediate-frequency band disturbance signal to form a sweep signal of a complete sweep cycle;

[0009] Step 2: The frequency sweep signal is passed as a reference signal to the disturbance source, the disturbance source generates a disturbance signal consistent with the reference signal, and the disturbance signal is injected into the system under test;

[0010] Step 3: Collect the input signal and feedback output signal of the node of the system to be tested when the disturbance source is connected; 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 band signal and the high-frequency band signal are synthesized and modulated, specifically:

[0012]

[0013] Among them, A1 is the amplitude of the high-frequency signal, f1 is the frequency of the high-frequency signal, is the initial phase of the high-frequency signal; A2 is the amplitude of the low-frequency signal, f2 is the frequency of the low-frequency signal, is the initial phase of the low-frequency signal; t1 is the total time required for the aliasing signal, f Lmin is the minimum frequency of the low-frequency signal; the maximum frequency of the high-frequency signal f Hmax , the minimum value f that the high-frequency signal can sweep to Hmin , the frequency sweep step length Δf of the high frequency signal H , the maximum frequency f of the low-frequency signal Lmax With minimum frequency f Lmin satisfy:

[0014] Furthermore, in step 1, the mid-frequency band signal is independently used to generate a mid-frequency band disturbance signal, specifically:

[0015]

[0016] Among them, A3 is the amplitude of the intermediate frequency signal, f3 is the frequency of the intermediate frequency signal, is the initial phase of the mid-frequency signal; t2 is the duration of the mid-frequency disturbance signal, f Mmax is the maximum frequency of the disturbance signal in the mid-frequency band, f Mmin is the minimum frequency of the disturbance signal in the mid-frequency band, Δf M is the frequency sweep step length of the intermediate frequency signal.

[0017] Furthermore, in step 3, a Butterworth filter is used to filter the collected signal, the low-frequency band signal and the high-frequency band signal are preprocessed by the Butterworth filter, and the mid-frequency band signal is directly called without preprocessing.

[0018] Furthermore, the design of the Butterworth band-stop filter requires that the passband and stopband boundary frequencies are symmetrical about the center frequency, and calibration is performed by the following steps:

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

[0020]

[0021] in, f s is the sampling frequency inside the sampling instrument;

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

[0023]

[0024] Step 3.3: Check whether the passband boundary frequency satisfies the symmetry; if ω p1 '=ω p2 ', then the passband boundary frequency is symmetrical and satisfies the symmetry, and no adjustment is required; otherwise, adjust the passband boundary frequency;

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

[0026]

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

[0028]

[0029] Step 3.6: Check whether the stopband boundary frequency satisfies the symmetry; if ω s1 '=ω s2 ', then the stopband boundary frequency symmetry satisfies the symmetry and does not need to be adjusted; 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 the difference equation;

[0031]

[0032] Among them, ω c 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, from the nth second to the n+mth second, the input disturbance frequency is searched, and after the disturbance is determined, the m-second signal is subjected to Fourier decomposition to decompose the voltage and current corresponding to the input disturbance frequency, and then the impedance is calculated. The calculation process is as follows:

[0034]

[0035] Among them, U(f) i and I(f) i They represent the voltage and current signals generated when the i-th disturbance frequency occurs, Z(f) i It means that the impedance corresponding to each frequency of the complete frequency sweep cycle is decomposed under the current disturbance frequency. The impedance is in the form of a complex number. The amplitude and phase angle of the impedance are calculated:

[0036]

[0037] Among them, Mag i represents the magnitude of the ith impedance Z(f)i, Phase i Represents the phase angle of impedance Z(f)i.

[0038] A computer device / equipment / system comprises 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 injecting disturbances in parallel.

[0039] A computer-readable storage medium stores a computer program / instruction, which, when executed by a processor, implements the steps of the method for obtaining system impedance by injecting disturbances in parallel.

[0040] A computer program product comprises a computer program / instruction, which, when executed by a processor, implements the steps of the method for obtaining system impedance by injecting disturbances in parallel.

[0041] The beneficial effects of the present invention are:

[0042] The present invention can generate a high- and low-frequency combined disturbance signal by means of a composite disturbance, and the signal can be directly used in the analysis and testing of system impedance. The present invention can simultaneously analyze the system impedance of multiple frequency bands by transmitting weakly coupled high and low frequency voltages to the power grid, which can effectively improve the frequency sweeping efficiency compared to the traditional single frequency. After injecting disturbances into the system to be tested, the sampled data obtained can separate high-frequency and low-frequency disturbances and feedback signals for a group of data, which can effectively shorten the total duration of the frequency sweeping and improve the efficiency of the frequency sweeping. The present invention has a short duration of disturbance for low-frequency and high-frequency systems, preventing the continuous disturbance of the disturbance source from having a cumulative impact on the system. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0044] Figure 2 The diagram is used to verify the mutual validity between theoretical modeling and simulation model.

[0045] Figure 3 Schematic diagram of the disturbance source model.

[0046] Figure 4 Schematic diagram of high-frequency and low-frequency aliasing cycles.

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

[0048] Figure 6 The present invention provides an overall flow chart of a method for obtaining system impedance by injecting disturbances in parallel. DETAILED DESCRIPTION

[0049] The present invention will be further described below in conjunction with the accompanying drawings.

[0050] The traditional small signal disturbance analysis method is to inject a disturbance signal of a single frequency into the power grid at the same time. The present invention injects high-frequency and low-frequency signals in parallel, and decouples the input disturbance and feedback disturbance of the two frequency bands to obtain the impedance corresponding to the two frequencies. The impedance analysis is performed by injecting two frequencies of sweep frequency, which can effectively shorten the time required for sweep frequency. The reduction of sweep frequency time can reduce the impact of small signal accumulation on the system. Parallel sweep frequency has weak coupling characteristics between low frequency and high frequency. In the data processing process, the voltage and current of each frequency can be directly filtered out by the filter. The signal processing method is simple and efficient.

[0051] A method for obtaining system impedance by parallel injection disturbances comprises the following steps:

[0052] Step 1: synthesize and modulate the low-frequency band signal and the high-frequency band signal to generate a synthesized disturbance signal; independently generate an intermediate-frequency band disturbance signal from the intermediate-frequency band signal; and continuously splice the synthesized disturbance signal and the intermediate-frequency band disturbance signal to form a sweep signal of a complete sweep cycle;

[0053] The low-frequency signal and the high-frequency signal are synthesized and modulated, specifically:

[0054]

[0055] Among them, A1 is the amplitude of the high-frequency signal, f1 is the frequency of the high-frequency signal, is the initial phase of the high-frequency signal; A2 is the amplitude of the low-frequency signal, f2 is the frequency of the low-frequency signal, is the initial phase of the low-frequency signal; t1 is the total time required for the aliasing signal, f Lmin is the minimum frequency of the low-frequency signal; the maximum frequency of the high-frequency signal f Hmax , the minimum value f that the high-frequency signal can sweep to Hmin , the frequency sweep step length Δf of the high frequency signal H , the maximum frequency f of the low-frequency signal Lmax With minimum frequency f Lmin satisfy:

[0056] The intermediate frequency signal is used to independently generate the intermediate frequency disturbance signal, specifically:

[0057]

[0058] Among them, A3 is the amplitude of the intermediate frequency signal, f3 is the frequency of the intermediate frequency signal, is the initial phase of the mid-frequency signal; t2 is the duration of the mid-frequency disturbance signal, f Mmax is the maximum frequency of the disturbance signal in the mid-frequency band, f Mmin is the minimum frequency of the disturbance signal in the mid-frequency band, Δf M is the frequency sweep step length of the intermediate frequency signal;

[0059] Step 2: The frequency sweep signal is passed as a reference signal to the disturbance source, the disturbance source generates a disturbance signal consistent with the reference signal, and the disturbance signal is injected into the system under test;

[0060] Step 3: Collect the input signal and feedback output signal of the node of the system to be tested when the disturbance source is connected; 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 collected signals are filtered using a Butterworth filter. The low-frequency and high-frequency signals are preprocessed by using a Butterworth filter, while the mid-frequency signals are directly called without preprocessing.

[0062] The design of the Butterworth band-stop filter requires that the passband and stopband boundary frequencies are symmetrical about the center frequency, and calibration is performed by the following steps:

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

[0064]

[0065] in, f s is the sampling frequency inside the sampling instrument;

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

[0067]

[0068] Step 3.3: Check whether the passband boundary frequency satisfies the symmetry; if ω p1 '=ω p2 ', then the passband boundary frequency is symmetrical and satisfies the symmetry, and no adjustment is required; otherwise, adjust the passband boundary frequency;

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

[0070]

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

[0072]

[0073] Step 3.6: Check whether the stopband boundary frequency satisfies the symmetry; if ω s1 '=ω s2 ', then the stopband boundary frequency symmetry satisfies the symmetry and does not need to be adjusted; 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 the difference equation;

[0075]

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

[0077] The filtered signal is first segmented from the nth second to the n+mth second to find the input disturbance frequency. After determining the disturbance, the m-second signal is subjected to Fourier decomposition to decompose the voltage and current corresponding to the input disturbance frequency. Then the impedance is calculated. The calculation process is as follows:

[0078]

[0079] Among them, U(f) i and I(f) i They represent the voltage and current signals generated when the i-th disturbance frequency occurs, Z(f) i It means that the impedance corresponding to each frequency of the complete frequency sweep cycle is decomposed under the current disturbance frequency. The impedance is in the form of a complex number. The amplitude and phase angle of the impedance are calculated:

[0080]

[0081] Among them, Mag i represents the magnitude of the ith impedance Z(f)i, Phase i Represents the phase angle of impedance Z(f)i.

[0082] Embodiment 1:

[0083] For the power system, which has a power frequency of 50 / 60Hz, the disturbance frequency is divided into a low frequency band of 1-10Hz, a medium frequency band of 10Hz-100Hz, and a high frequency band above 100Hz. Since the medium frequency band parameters and system coupling are easy to produce coupling with the power frequency, it is usually necessary to avoid the aliasing of the medium frequency band signal and the power frequency signal in this frequency sweep. Therefore, when performing parallel frequency sweeps, the low frequency and high frequency are synthesized and modulated. In addition to the synthesized modulation signal, the signal in the medium frequency band independently generates a reference signal. The reference signal and the synthesized signal are continuously spliced ​​together to form a sweep signal with a complete sweep cycle. The sweep signal is passed to the disturbance source as a reference. The disturbance source generates a disturbance signal consistent with the reference wave, and the generated disturbance is injected into the system to be tested. The system disturbance flow chart is as follows: Figure 1 shown.

[0084] Use the instrument to collect and record the input signal and feedback output signal of the disturbance source access node. Separate the collected signals to separate high-frequency input and output signals and low-frequency input and output signals. Calculate the parameters of the corresponding frequencies based on the input and output signals. When the disturbance input is voltage and the feedback is current, the system conductance is required; when the disturbance input is current and the feedback is voltage, the system impedance is required. Mark all the calculated parameters one by one in the Bode diagram through the calculation software, and compare the Bode diagram of the theoretical modeling with the actual Bode diagram to ensure that the theoretical modeling is consistent with the actual.

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

[0086] The impedance or admittance parameters of the system are calculated and analyzed using specific impedance modeling methods, including dq impedance modeling, positive and negative sequence impedance modeling or harmonic linearization, etc. All devices in the system are equivalently modeled to build an overall theoretical model.

[0087]

[0088] 2. Simulation model construction:

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

[0090] 3. Establish disturbance source model:

[0091] In the Matlab environment, a controlled voltage source or a controlled current source is established, and the controlled source is connected to the node to be tested. The controlled interface is well-made to support the generation of disturbance reference waveforms, such as Figure 3 shown.

[0092] 4. Design disturbance generation algorithm:

[0093] Assume that the frequency generation function of low frequency is 1Hz-10Hz low frequency band and 100Hz high frequency band. Design the generation logic and control algorithm of high frequency signal and low frequency signal at the same time. Combine the two into disturbance signal by superposition and give the signal to the established controlled source. Test its function in the environment. The specific calculation method of disturbance source generation function is as follows:

[0094]

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

[0096]

[0097] 5. Set the sweep rule sequence:

[0098] After completing the preparations in 1-4, set the sweep parameters including:

[0099] ① Disturbance frequency;

[0100] ② Duration of disturbance;

[0101] When performing a full-cycle frequency sweep, the time and cycle required for the low-frequency sweep interval system are longer, so based on the time required for the low-frequency cycle, multiple high-frequency cycles are mixed into one low-frequency cycle. Frequency segmentation is usually divided into three frequency bands, and the frequency intervals are:

[0102] ①Low frequency: 0.1-10Hz

[0103] ②Intermediate frequency: 10-100Hz

[0104] ③High 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 is the maximum frequency value of the high frequency band, f Hmin is the minimum value that can be swept in the high frequency band, Δf H is the frequency sweep step length of the high frequency band, fLmax is the maximum frequency in the low frequency band, f Lmin is the minimum frequency in the low frequency band. t1 is the total time required for the aliasing signal.

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

[0109] Usually, low frequency and high frequency are based on a fixed period of 0.1s, and the high frequency step is 10Hz, that is, within 10s of the entire low frequency sweep band, the high frequency band can be scanned from 100Hz to 1000Hz at the same time. The high frequency step size can also be changed. For example, if the high frequency band step is set to 20Hz, the scan from 100Hz to 1900Hz can be achieved.

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

[0111]

[0112] The time required for traditional frequency sweep is t L +t M +t H , the total duration t1+t2 can be achieved through this method, and the total duration can be greatly shortened.

[0113] 5. Actual machine verification:

[0114] In the actual machine, the disturbance characteristics mentioned in this embodiment are connected to the power grid to be tested as the disturbance source reference signal source, and the disturbance signal is injected into the power grid. The input and feedback signals of the system are measured and recorded by professional instruments, such as Figure 5 shown.

[0115] 6. Acquisition signal processing:

[0116] Since the system has no real-time requirements for the data collected after completing the frequency sweep, the designed Butterworth filter can be used to preprocess the data for the high-frequency and low-frequency signals of the composite modulation. The intermediate frequency signal can be directly called without preprocessing, and the sampled signal can be directly called. The processed design performs data conversion and processing on the sampled data, and then processes the collected data through the filtering algorithm to obtain the high-frequency and low-frequency signal waveforms respectively. The signal in the intermediate frequency band can be directly processed without a filter. The processing flow is as follows:

[0117] (1) Clarify requirements and technical indicators

[0118] The following technical indicators are specified:

[0119] Passband edge frequency: f Lmax , fHmin ;

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

[0121] Maximum passband attenuation: A p ;

[0122] Stopband minimum attenuation: A s ;

[0123] Sampling frequency: The sampling frequency (f s )Decide;

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

[0125] (2) Standardized frequency calculation

[0126] Convert these frequency specifications to standard frequencies relative to the Nyquist frequency.

[0127] Nyquist frequency:

[0128] Normalized passband edge frequency:

[0129] Normalized stopband edge frequency:

[0130] (3) Geometric symmetry calibration

[0131] The design of the Butterworth band-stop filter requires that the passband and stopband boundary frequencies are symmetrical about the center frequency. Calibration is performed by the following steps:

[0132] 1) Calculate the passband center frequency:

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

[0134] 3) Check whether the symmetry is satisfied: when ω p1 '=ω p2 ', the passband is symmetrical and no adjustment is required.

[0135] The stopband boundary frequencies also need to be symmetrical, 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 ', the passband is symmetrical and no adjustment is required. If they are not the same, adjust the boundary frequency.

[0139] (4) Determine the filter function

[0140] The transfer function of the Basworth filter is:

[0141]

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

[0143]

[0144] Where T is the sampling period, Substituting s yields the final z-domain transfer function.

[0145] (5) Implementing digital filter

[0146] With the z-domain transfer function, we can decompose it into a number of second-order filter segments and implement the filter by calculating the poles and zeros. Expand the z-domain transfer function, find the poles and zeros, and then implement each filter segment through the difference equation.

[0147] 7. Data consistency check

[0148] After filtering, the signal separated into three frequency bands is subjected to FFT decomposition, and the impedance corresponding to each frequency of the full cycle of the system is decomposed, and its amplitude and phase angle are calculated. The results of all frequencies obtained by frequency sweeping are plotted on the Bode diagram, and finally the impedance rapid scanning result is obtained. The result and the result of the theoretical modeling done before are plotted on the same Bode diagram through software, and the credibility can be increased by consistency verification. From the results of the sampling data, the present invention can effectively improve the information density of the data, and a set of multi-frequency disturbance data can obtain two sets of impedances, effectively improving data utilization.

[0149] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for obtaining system impedance by parallel injection disturbance, characterized in that: The following steps are involved: Step 1: synthesize and modulate the low-frequency band signal and the high-frequency band signal to generate a synthesized disturbance signal; independently generate an intermediate-frequency band disturbance signal from the intermediate-frequency band signal; and continuously splice the synthesized disturbance signal and the intermediate-frequency band disturbance signal to form a sweep signal of a complete sweep cycle; Step 2: The frequency sweep signal is passed as a reference signal to the disturbance source, the disturbance source generates a disturbance signal consistent with the reference signal, and the disturbance signal is injected into the system under test; Step 3: Collect the input signal and feedback output signal of the node of the system to be tested when the disturbance source is connected; 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 disturbance according to claim 1, characterized in that: In step 1, the low-frequency band signal and the high-frequency band signal are synthesized and modulated, specifically: Among them, A1 is the amplitude of the high-frequency signal, f1 is the frequency of the high-frequency signal, is the initial phase of the high-frequency signal; A2 is the amplitude of the low-frequency signal, f2 is the frequency of the low-frequency signal, is the initial phase of the low-frequency signal; t1 is the total time required for the aliasing signal, f Lmin is the minimum frequency of the low-frequency signal; the maximum frequency of the high-frequency signal f Hmax , the minimum value f that the high-frequency signal can sweep to Hmin , the frequency sweep step length Δf of the high frequency signal H , the maximum frequency f of the low-frequency signal Lmax With minimum frequency f Lmin satisfy:

3. The method for obtaining system impedance by parallel injection disturbance according to claim 2, characterized in that: In step 1, the intermediate frequency signal is used to independently generate the intermediate frequency disturbance signal, specifically: Among them, A3 is the amplitude of the intermediate frequency signal, f3 is the frequency of the intermediate frequency signal, is the initial phase of the mid-frequency signal; t2 is the duration of the mid-frequency disturbance signal, f Mmax is the maximum frequency of the disturbance signal in the mid-frequency band, f Mmin is the minimum frequency of the disturbance signal in the mid-frequency band, Δf M is the frequency sweep step length of the intermediate frequency signal.

4. The method for obtaining system impedance by parallel injection disturbance according to claim 3, characterized in that: In the step 3, a Butterworth filter is used to filter the collected signal, the low-frequency band signal and the high-frequency band signal are preprocessed by the Butterworth filter, and the mid-frequency band signal is directly called without preprocessing.

5. The method for obtaining system impedance by parallel injection disturbance according to claim 4, characterized in that: The design of the Butterworth band-stop filter requires that the passband and stopband boundary frequencies are symmetrical about the center frequency, and calibration is performed by the following steps: Step 3.1: Calculate the passband center frequency; in, f s is the sampling frequency inside the sampling instrument; Step 3.2: Calculate the passband edge frequency; Step 3.3: Check whether the passband boundary frequency satisfies the symmetry; if ω p1 '=ω p2 ', then the passband boundary frequency is symmetrical and satisfies the symmetry, and no adjustment is required; otherwise, adjust the passband boundary frequency; Step 3.4: Calculate the stopband center frequency; Step 3.5: Calculate the stopband edge frequency; Step 3.6: Check whether the stopband boundary frequency satisfies the symmetry; if ω s1 '=ω s2 ', then the stopband boundary frequency symmetry satisfies the symmetry and does not need to be adjusted; 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 the difference equation; Among them, ω c is the edge cutoff frequency, and N is the order of the Butterworth band-stop filter.

6. The method for obtaining system impedance by parallel injection disturbance according to claim 5, 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 searched, and after the disturbance is determined, the m-second signal is Fourier decomposed to decompose the voltage and current corresponding to the input disturbance frequency, and then the impedance is calculated. The calculation process is as follows: Among them, U(f) i and I(f) i They represent the voltage and current signals generated when the i-th disturbance frequency occurs, Z(f) i It means that the impedance corresponding to each frequency of the complete frequency sweep cycle is decomposed under the current disturbance frequency. The impedance is in the form of a complex number. The amplitude and phase angle of the impedance are calculated: Among them, Mag i represents the magnitude of the ith impedance Z(f)i, Phase i Represents the phase angle of impedance Z(f)i.

7. 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 6.

8. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer program product comprising a computer program / instructions, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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