Frequency spectrum extraction method and device capable of resisting non-target frequency interference for impedance measurement

Abstract

The invention discloses an anti-non-target frequency interference spectrum extraction method and device for impedance measurement, and relates to the technical field of power system analysis. The method comprises the following steps: acquiring response data of a tested system; the operation frequency of the tested system is obtained based on the response data, the response data and the operation frequency are input into a band elimination filter, and first output is obtained; a target frequency band of impedance measurement is divided into a plurality of continuous frequency band intervals, the frequency band interval where background harmonic frequency is located is determined from the multiple frequency band intervals, a band elimination filter bank is designed in the frequency band interval where the background harmonic frequency is located, and the band elimination filter bank is formed by connecting a plurality of band elimination filters with equal-interval inherent frequency in series; inputting the first output into the band elimination filter bank to obtain a second output; and performing FFT conversion on the second output to obtain a target frequency spectrum. According to the method, non-target frequency interference is filtered out, so that the accuracy of a spectrum extraction result is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power system analysis, and in particular to a spectrum extraction method and device for impedance measurement that is resistant to non-target frequency interference. Background Art

[0002] With the rapid development of renewable energy power generation technology, more and more voltage source converters (VSC) are connected to the power supply system. The impedance (output characteristics) between the VSC type converter equipment and the power network does not match, resulting in underdamping or negative damping in the system in a specific frequency band, causing system oscillation / instability problems. Therefore, accurately obtaining the broadband impedance characteristics of the power supply system is of great significance to ensure the safe and stable operation of the renewable energy power generation system.

[0003] The impedance measurement of the power supply system is a key way to obtain the wideband impedance characteristics of the system. The general steps of impedance measurement are: S1. Inject the target frequency harmonic disturbance into the power supply system under test; S2. Collect the response data of the system under test; S3. Extract the target frequency spectrum; S4. Impedance calculation.

[0004] Among them, in the process of extracting the target frequency spectrum in S3, the prior art usually adopts conventional FFT, or performs FFT transformation on the collected data after windowing function processing, and extracts the target frequency spectrum information. However, this extraction method is greatly affected by the non-target frequency interference such as the deviation of the operating frequency of the power supply system from the power frequency and the existence of background harmonics, which greatly affects the accuracy of the impedance measurement results. When the operating frequency of the power supply system deviates from the power frequency, directly performing FFT transformation on the collected response data will cause spectrum leakage. The windowing function method can suppress the phenomenon of spectrum leakage, but it will change the collected time domain data, change the spectrum information, and cause the target frequency spectrum information to be extracted inaccurately. In addition, if the background harmonics of the power supply system fall in the frequency band between the target frequencies of the impedance measurement, spectrum aliasing will occur when the FFT transformation is performed directly, interfering with the accurate extraction of the target frequency spectrum.

[0005] In view of this, the present invention proposes a spectrum extraction method for resisting non-target frequency interference suitable for power supply system impedance measurement to solve the problem of non-target interference. Summary of the invention

[0006] The present invention provides a spectrum extraction method and device for impedance measurement that is resistant to non-target frequency interference, so as to solve the problem that the existing FFT-based target frequency extraction method is interfered by the non-target frequency of the power supply system itself, and the extracted spectrum affects the impedance measurement accuracy.

[0007] The present invention is achieved through the following technical solutions:

[0008] A first aspect of the present invention provides a spectrum extraction method for impedance measurement that is resistant to non-target frequency interference, comprising:

[0009] Acquiring response data of the system under test, the response data being generated after injecting a target frequency harmonic disturbance into the system under test;

[0010] Obtaining an operating frequency of the system under test based on the response data, inputting the response data and the operating frequency into a band-stop filter to obtain a first output;

[0011] Divide the target frequency band of impedance measurement into a plurality of continuous frequency band intervals, determine the frequency band interval where the background harmonic frequency is located from the plurality of frequency band intervals, and design a band stop filter group within the frequency band interval where the background harmonic frequency is located, wherein the band stop filter group is composed of a plurality of band stop filters with equally spaced natural frequencies connected in series;

[0012] Inputting the first output into the band-stop filter bank to obtain a second output;

[0013] Perform FFT transformation on the second output to obtain a target frequency spectrum.

[0014] In view of the operating frequency deviation from the power frequency and the background harmonic interference in the power supply system, the present invention adopts a method of filtering out non-target frequency interference to improve the accuracy of the target frequency spectrum extraction, so as to improve the accuracy of the impedance measurement results. First, the response data and the system operating frequency are band-stop filtered by a band-stop filter to obtain a first output, and then the first output is subjected to an FFT transformation to extract the target frequency spectrum information of the anti-power supply system operating frequency deviation from the power frequency; then, an equally spaced natural frequency band-stop filter group is designed in the background harmonic frequency interval, and the first output is filtered to filter out the background harmonics. So far, the influence of the operating frequency deviation from the power frequency and the background harmonics on the extraction of the target frequency spectrum is avoided, and then the obtained second output is subjected to an FFT transformation to obtain accurate target frequency spectrum information.

[0015] Further, obtaining the operating frequency of the system under test based on the response data includes: passing the response data through a bandpass filter and a phase-locked loop in sequence to obtain the operating frequency of the system under test.

[0016] Furthermore, the bandwidth of each of the frequency band intervals is equal to the resolution of the impedance measurement frequency.

[0017] Furthermore, in the order of series connection, the natural frequency of the first band-stop filter in the band-stop filter group is the lower limit of the frequency band interval where the background harmonic frequency is located, and the natural frequency of the last band-stop filter is the upper limit of the frequency band interval where the background harmonic frequency is located, and the natural frequency interval is f n0 =fres / (m+1), where f res is the resolution of the impedance measurement frequency, and m is the number of filters in the band-stop filter bank.

[0018] Furthermore, in the band-stop filter bank, the natural frequency of the ith band-stop filter in the series order is fn i=f min +(n-1)f res +if n0 , where f min is the lower limit of the first frequency band, f res is the impedance measurement frequency resolution, f n0 is the natural frequency interval of the band-stop filter group, n represents the serial number of the frequency band where the background harmonic frequency is located, that is, f min +(n-1)f res It is the lower limit of the frequency band where the background harmonic frequency is located.

[0019] Furthermore, before performing FFT transformation on the second output, the method further comprises: compensating the second output according to an amplitude-frequency characteristic curve of the band-stop filter group.

[0020] A second aspect of the present invention provides a spectrum extraction device for impedance measurement and resisting non-target frequency interference, comprising:

[0021] A data acquisition module, used to acquire response data of the system under test, wherein the response data is generated after injecting a target frequency harmonic disturbance into the system under test;

[0022] A first data processing module, configured to obtain an operating frequency of the system under test based on the response data, and perform a band-stop filtering process on the response data in combination with the operating frequency to obtain a first output;

[0023] The second data processing module includes a band-stop filter group composed of a plurality of band-stop filters with equally spaced natural frequencies connected in series, and is used to filter the first output to obtain a second output; the design method of the band-stop filter group is:

[0024] Dividing the target frequency band of impedance measurement into a plurality of continuous frequency band intervals, determining the frequency band interval where the background harmonic frequency is located from the plurality of frequency band intervals, and designing a band stop filter group within the frequency band interval where the background harmonic frequency is located;

[0025] The FFT module is used to perform FFT transformation on the second output data to obtain a target frequency spectrum.

[0026] Further, the first data processing module includes a bandpass filter, a phase-locked loop and a band-stop filter connected in series;

[0027] The response data passes through the bandpass filter and the phase-locked loop to obtain the operating frequency of the system under test, and the response data and the operating frequency pass through the bandstop filter to obtain a first output.

[0028] In a third aspect of the present invention, an electronic device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the spectrum extraction method for impedance measurement against non-target frequency interference as described in any one of the first aspects of the present invention is implemented.

[0029] According to a fourth aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the spectrum extraction method for impedance measurement against non-target frequency interference as described in any one of the first aspects of the present invention is implemented.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] Considering the interference of background harmonics and the deviation of the operating frequency of the power supply system from the power frequency on spectrum extraction, a spectrum extraction method with resistance to non-target frequency interference suitable for power supply system impedance measurement is provided. By filtering out non-target frequency interference, the accuracy of spectrum extraction results is improved.

[0032] Since the band-stop filter group will attenuate the target frequency values ​​at both ends of the frequency band where the background harmonic frequency is located, the second output is compensated according to the amplitude-frequency characteristic curve of the band-stop filter group, making the FFT extraction result more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0034] Figure 1 It is a flow chart of a spectrum extraction method for impedance measurement and resisting non-target frequency interference according to an embodiment of the present invention;

[0035] Figure 2 is a schematic diagram of a response data processing method according to an embodiment of the present invention;

[0036] Figure 3 is an amplitude-frequency characteristic curve of a band-stop filter group according to an embodiment of the present invention;

[0037] Figure 4 It is the target frequency spectrum result extracted by the method of the present invention;

[0038] Figure 5 It is the target frequency spectrum result extracted directly by FFT. DETAILED DESCRIPTION

[0039] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0040] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to or inherent to other steps or units of the device.

[0041] The terms used in the various embodiments of the application are only used to describe the purpose of specific embodiments and are not intended to limit the various embodiments of the application. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise limited, all terms used here (including technical terms and scientific terms) have the same meaning as the meanings commonly understood by ordinary technicians in the field of the various embodiments of the application. The terms (such as the terms defined in the dictionary generally used) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning, unless clearly defined in the various embodiments of the application.

[0042] The embodiments of the present invention provide a spectrum extraction method and device for impedance measurement that is resistant to non-target frequency interference, which is applicable to impedance measurement of power systems and is conducive to improving the accuracy of detection results.

[0043] like Figure 1 As shown, Figure 1 It is a flow chart of a spectrum extraction method for impedance measurement with resistance to non-target frequency interference provided by an embodiment of the present invention, which includes the following execution steps.

[0044] S1, obtain the response data of the system under test.

[0045] Among them, the response data is collected after injecting the target frequency harmonic disturbance into the system under test. The impedance sweep measurement method based on harmonic disturbance injection is a mature existing technology and is not the focus of the present invention.

[0046] S2, obtaining the operating frequency of the system under test based on the response data, inputting the response data and the operating frequency into a band-stop filter to obtain a first output.

[0047] like Figure 2 The response data processing method shown in the figure uses the illustrated method to process the response data, firstly obtaining the power supply system operating frequency f0, wherein Gbp(s) is a bandpass filter, PLL is a phase-locked loop, Gbs(s) is a bandstop filter, and f0 is the identified power supply system operating frequency. Then the response data and the identified power supply system operating frequency f0 are sent to the bandstop filter Gbs(s) to obtain the processed output data.

[0048] Figure 2 The figure shows a method for obtaining the system operating frequency f0 according to an embodiment of the present invention, that is, the response data is sequentially passed through a bandpass filter and a phase-locked loop to obtain the operating frequency of the system under test. Other identification methods can also be used to obtain f0, such as a low-pass filter + phase-locked loop, and a zero-crossing measurement method.

[0049] This step mainly deals with the interference caused by the deviation of the operating frequency of the power supply system from the power frequency. By inputting the response data and the operating frequency into the band-stop filter, the band-stop filter can filter out f0, thereby eliminating the interference of f0. The first output obtained eliminates the influencing factors of the deviation from the power frequency interference. Then, the first output is transformed by FFT to extract the target frequency spectrum information to resist the deviation of the operating frequency of the power supply system from the power frequency.

[0050] S3, dividing the target frequency band of impedance measurement into a plurality of continuous frequency band intervals, determining the frequency band interval where the background harmonic frequency is located from the plurality of frequency band intervals, and designing a band stop filter group within the frequency band interval where the background harmonic frequency is located.

[0051] The band-stop filter is designed to resist background harmonic interference. The target frequency band of the impedance measurement is a known parameter and is usually set manually before the impedance measurement. For example, the target frequency band range is (f min , f max ), divide it into n continuous intervals, each interval is f res , then we get: The first interval (f min , f min +f res ), the second interval (f min +f res , f min +2f res ), the third interval (f min +2f res , f min +3f res ), ..., the nth interval: (f min +(n-1)fres , f max ), n=(f max -f min ) / f res .

[0052] In one embodiment, the bandwidth f of each frequency band interval is res The resolution of the impedance measurement frequency.

[0053] Resolution refers to the frequency at which a point is measured every so many Hz during impedance measurement. For example, if the impedance frequency points measured are 10Hz, 20Hz, 30Hz, ..., then the frequency resolution is 10Hz. The measurement frequency resolution is consistent with the injected harmonic frequency, and the frequency of the injected harmonic is the impedance frequency to be measured. In this way, this method can filter out the harmonic interference between the target measurement frequencies, such as the frequency interference between 10Hz to 20Hz, 20Hz to 30Hz, ...

[0054] The background harmonics can be roughly distributed by FFT analysis, and a band-stop filter group is set in the frequency band interval where the background harmonics are located. Specifically, the band-stop filter group is composed of a plurality of band-stop filters with equally spaced natural frequencies connected in series. According to the order of series connection, the natural frequency of the first band-stop filter in the band-stop filter group is the lower limit of the frequency band interval where the background harmonics are located, and the natural frequency of the last band-stop filter is the upper limit of the frequency band interval where the background harmonics are located. If the frequency band interval where the background harmonics are located is the nth frequency band interval, the frequency band range of the nth frequency band interval is (f min +(n-1)f res , f min +nf res ). The transfer function of the band-stop filter bank is expressed as: F(s) = G bs1 (s)+G bs2 (s)+...+G bsm (s), the natural frequency interval is f n0 =f res / (m+1), band-stop filter G bs1 The natural frequency of (s) is set to: f n1 =f min +(n-1)·f res +f n0 , band-stop filter G bs2 The natural frequency of (s) is set to f n2 =f min +(n-1)·f res +2·f n0 , and so on, the band-stop filter G bsm The natural frequency of (s) is set to f nm =f min+(n-1)·f res +m·f n0 .

[0055] S4, input the first output into a band-stop filter group to obtain a second output.

[0056] The band-stop filter group is designed within the background harmonic frequency range to filter out the background harmonics. Therefore, the data output by the filter F(s) is subjected to FFT transformation to avoid the influence of the background harmonics.

[0057] S5, performing FFT transformation on the second output to obtain a target frequency spectrum.

[0058] After the response data passes through S2 and S4, the influence of the power supply system operating frequency deviating from the power frequency and the background harmonic frequency are eliminated in turn, so that after FFT transformation, the extracted target frequency spectrum result is more accurate.

[0059] Furthermore, a set of actual test data was used to compare and verify the above-disclosed spectrum extraction results for impedance measurement against non-target frequency interference and the results of direct extraction using FFT.

[0060] The power supply system operating frequency used in the actual test is 49Hz, which deviates from the conventional power frequency (50Hz), and the background harmonic is 147Hz. res The target frequency spectrum range is 100 Hz to 340 Hz. The steps S1 to S5 in the above embodiment are performed on the test system.

[0061] Step 1: First, the response data of the power supply system under test is collected. The acquisition time t and the power supply system impedance measurement frequency resolution f res Related, t = 1 / f res =0.1s.

[0062] Step 2: Use Figure 2 The method shown processes the response data. First, the power supply system operating frequency f0 is obtained through the bandpass filter Gbp(s) and the phase-locked loop PLL, and then the response data and the power supply system operating frequency f0 (49Hz) are sent to the bandstop filter Gbs(s) to obtain the processed first output.

[0063] Step 3: Measure the frequency resolution f according to the power supply system impedance res A band-stop filter bank is designed for the target frequency band (10Hz) and target frequency band (100Hz, 340Hz).

[0064] The target frequency band (100 Hz, 340 Hz) of impedance measurement is divided into n intervals, n = (f max -fmin ) / f res =24, respectively: the 1st interval (100Hz, 110Hz), the 2nd interval (110Hz, 120Hz), the 3rd interval (120Hz, 130Hz), ..., the 24th interval: (330Hz, 340Hz).

[0065] A band-stop filter group F(s) is set in the fifth interval (140 Hz, 150 Hz) where the background harmonic 147 Hz is located. F(s) is composed of m (m=9 in this embodiment) band-stop filters G with equal natural frequency intervals. bs (s) are connected in series, and its transfer function is: F(s) = G bs1 (s)+G bs2 (s)+...+G bs9 (s), the natural frequency interval is: f n0 =f res / (m+1)=1Hz. Therefore, the band-stop filter G bs1 The natural frequency of (s) is set to f n1 =f min +(n-1)·f res +f n0 =141Hz, band-stop filter G bs2 The natural frequency of (s) is set to f n2 =f min +(n-1)·f res +2·f n0 =142Hz, and so on, the band-stop filter G bs9 The natural frequency of (s) is set to f nm =f min +(n-1)·f res +m·f n0 =149Hz.

[0066] Step 4: Send the output data of step 2 to the band-stop filter group F(s) to obtain the second output.

[0067] The amplitude-frequency characteristic curve of the band-stop filter group F(s) is as follows: Figure 3 As shown, the band-stop filter group F(s) will attenuate the target frequency values ​​at both ends of the interval. Figure 3 The corresponding value at the target frequency values ​​at both ends of the middle background harmonic interval (140Hz, 150Hz) is 0.7, that is, the attenuation factor σ is 0.7.

[0068] Therefore, in one embodiment of the present invention, considering that the filter F(s) may attenuate the target frequency values ​​at both ends of the interval, the second output is compensated according to the amplitude-frequency characteristic curve of the band-stop filter group.

[0069] Specifically, an attenuation factor is used to compensate the target frequency values ​​at both ends of the interval, and the compensation coefficient is τ=1 / σ≈1.43.

[0070] Step 5: Perform FFT transformation on the data output by the filter F(s).

[0071] By performing FFT transformation on the data output by F(s), the influence of background harmonics can be avoided. Figure 4 The target frequency spectrum extracted by the method of the present invention is shown in FIG. Figure 5 The figure shows the target frequency spectrum result extracted directly by FFT. It can be seen that the extracted target frequency spectrum is evenly distributed and more accurate than the result extracted directly by FFT.

[0072] An embodiment of the present invention further provides a spectrum extraction device for impedance measurement that resists non-target frequency interference, and the device is used to execute the spectrum extraction method for impedance measurement that resists non-target frequency interference of any of the above embodiments of the present invention. The device comprises:

[0073] A data acquisition module, used to acquire response data of the system under test, wherein the response data is generated after injecting a target frequency harmonic disturbance into the system under test;

[0074] A first data processing module, configured to obtain an operating frequency of the system under test based on the response data, and perform a band-stop filtering process on the response data in combination with the operating frequency to obtain a first output;

[0075] The second data processing module includes a band-stop filter group composed of a plurality of band-stop filters with equally spaced natural frequencies connected in series, and is used to filter the first output to obtain a second output; the design method of the band-stop filter group is:

[0076] Dividing the target frequency band of impedance measurement into a plurality of continuous frequency band intervals, determining the frequency band interval where the background harmonic frequency is located from the plurality of frequency band intervals, and designing a band stop filter group within the frequency band interval where the background harmonic frequency is located;

[0077] The FFT module is used to perform FFT transformation on the second output data to obtain a target frequency spectrum.

[0078] Further, provide Figure 2 The first data processing module comprises a bandpass filter, a phase-locked loop and a band-stop filter connected in series; the response data passes through the bandpass filter and the phase-locked loop to obtain the operating frequency of the system under test, and the response data and the operating frequency pass through the band-stop filter to obtain a first output.

[0079] An embodiment of the present invention further provides an electronic device, including a processor and a memory. The number of processors in the computer device may be one or more. The memory, as a computer-readable storage medium, can be used to store software programs, computer executable programs, and modules. The processor executes various functional applications and data processing of the electronic device by running the software programs, instructions, and modules stored in the memory, so as to implement the spectrum extraction method for impedance measurement with resistance to non-target frequency interference according to any of the above embodiments of the present invention.

[0080] The memory may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system and an application required for at least one function; the data storage area may store data created according to the use of the terminal, etc. In addition, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some instances, the memory may further include a memory remotely arranged relative to the processor, and these remote memories may be connected to the electronic device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0081] An embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, a spectrum extraction method for impedance measurement with resistance to non-target frequency interference according to any embodiment of the present invention is implemented. The storage medium may be a ROM / RAM, a magnetic disk, an optical disk, etc.

[0082] An embodiment of the present invention further provides a computer program product. When the computer program product is run on a computer, the computer executes the spectrum extraction method for impedance measurement and resisting non-target frequency interference according to any of the above embodiments of the present invention.

[0083] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A spectrum extraction method for impedance measurement with immunity to non-target frequency interference, characterized in that: include: Acquiring response data of the system under test, the response data being generated after injecting a target frequency harmonic disturbance into the system under test; Obtaining an operating frequency of the system under test based on the response data, inputting the response data and the operating frequency into a band-stop filter to obtain a first output; Divide the target frequency band of impedance measurement into a plurality of continuous frequency band intervals, determine the frequency band interval where the background harmonic frequency is located from the plurality of frequency band intervals, and design a band stop filter group within the frequency band interval where the background harmonic frequency is located, wherein the band stop filter group is composed of a plurality of band stop filters with equally spaced natural frequencies connected in series; Inputting the first output into the band-stop filter bank to obtain a second output; Perform FFT transformation on the second output to obtain a target frequency spectrum.

2. The spectrum extraction method for impedance measurement against non-target frequency interference according to claim 1, characterized in that: The obtaining the operating frequency of the system under test based on the response data includes: passing the response data through a bandpass filter and a phase-locked loop in sequence to obtain the operating frequency of the system under test.

3. The spectrum extraction method for impedance measurement against non-target frequency interference according to claim 1, characterized in that: The bandwidth of each frequency band interval is equal to the resolution of the impedance measurement frequency.

4. The spectrum extraction method for impedance measurement against non-target frequency interference according to claim 3, characterized in that: In the order of series connection, the natural frequency of the first band-stop filter in the band-stop filter group is the lower limit of the frequency band interval where the background harmonic frequency is located, and the natural frequency of the last band-stop filter is the upper limit of the frequency band interval where the background harmonic frequency is located. The natural frequency interval is f n0 =f res / (m+1), where f res is the resolution of the impedance measurement frequency, and m is the number of filters in the band-stop filter bank.

5. The spectrum extraction method for impedance measurement with resistance to non-target frequency interference according to claim 4, characterized in that: In the band-stop filter bank, the natural frequency of the ith band-stop filter in the series order is f ni =f min +(n-1)f res +if n0 , where f min is the lower limit of the first frequency band, f res is the impedance measurement frequency resolution, f n0 is the natural frequency interval of the band-stop filter group, n represents the serial number of the frequency band where the background harmonic frequency is located, that is, f min +(n-1)f res It is the lower limit of the frequency band where the background harmonic frequency is located.

6. The spectrum extraction method for impedance measurement with resistance to non-target frequency interference according to any one of claims 1 to 5, characterized in that: Before performing FFT transformation on the second output, the method further includes: compensating the second output according to an amplitude-frequency characteristic curve of the band-stop filter group.

7. A spectrum extraction device for impedance measurement with immunity to non-target frequency interference, characterized in that: include: A data acquisition module, used to acquire response data of the system under test, wherein the response data is generated after injecting a target frequency harmonic disturbance into the system under test; A first data processing module, configured to obtain an operating frequency of the system under test based on the response data, and perform a band-stop filtering process on the response data in combination with the operating frequency to obtain a first output; The second data processing module includes a band-stop filter group composed of a plurality of band-stop filters with equally spaced natural frequencies connected in series, and is used to filter the first output to obtain a second output; the design method of the band-stop filter group is: Dividing the target frequency band of impedance measurement into a plurality of continuous frequency band intervals, determining the frequency band interval where the background harmonic frequency is located from the plurality of frequency band intervals, and designing a band stop filter group within the frequency band interval where the background harmonic frequency is located; The data calculation module is used to perform FFT transformation on the second output data to obtain a target frequency spectrum.

8. The spectrum extraction device for impedance measurement and resisting non-target frequency interference according to claim 7, characterized in that: The first data processing module includes a bandpass filter, a phase-locked loop and a band-stop filter connected in series; The response data passes through the bandpass filter and the phase-locked loop to obtain the operating frequency of the system under test, and the response data and the operating frequency pass through the bandstop filter to obtain a first output.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the spectrum extraction method for impedance measurement against non-target frequency interference as described in any one of claims 1 to 6 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the spectrum extraction method for impedance measurement and resisting non-target frequency interference according to any one of claims 1 to 6 is implemented.

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