A method and system for measuring power frequency impedance of a power line

Abstract

This invention discloses a method and system for measuring power frequency impedance of a power line. The method includes: performing phase rotation decomposition on the voltage sub-signal and current sub-signal of each target injection point according to a preset signal decomposition strategy; using the average value of the decomposed components as the voltage fusion component and current fusion component corresponding to the voltage sub-signal and current sub-signal of each target injection point; calculating the resistance and reactance values ​​at each frequency point based on the voltage and current fusion components; and generating resistance-frequency curves and reactance-frequency curves based on the signal quality at each frequency point; and reading the power frequency resistance and reactance values ​​within the power frequency neighborhood of the resistance-frequency curve and reactance-frequency curve, respectively. This makes the calculation results closer to the true values ​​and improves measurement accuracy.

Description

Technical Field

[0001] This invention belongs to the field of impedance measurement technology, and in particular relates to a method and system for measuring the power frequency impedance of a line. Background Technology

[0002] The power frequency impedance of power lines is a core parameter for evaluating line transmission performance, fault location, and insulation condition. Traditional measurement methods are mainly divided into two categories:

[0003] Direct power frequency measurement method: Impedance is calculated by directly acquiring voltage / current signals under power frequency (50Hz / 60Hz) conditions. However, background harmonics in the power grid, load fluctuations, and noise interference result in a low signal-to-noise ratio and a large measurement error. If filtering and noise reduction are used, phase distortion will be introduced, affecting the accuracy of reactance.

[0004] Frequency sweep injection method: Injecting a non-power frequency test current signal into the line and scanning the target frequency band point by point. Although it can avoid power frequency interference, it requires multiple sequential injections (e.g., 10 independent operations are required for 10 frequency points), and each measurement takes a long time. For long-distance transmission lines, changes in system operating conditions during the test can lead to poor data consistency, and frequent start-stop operations can easily damage the power electronic injection equipment. Summary of the Invention

[0005] This invention provides a method and system for measuring power frequency impedance of a power line, which solves the technical problem of being unable to extract the power frequency impedance of a power line quickly and accurately in a strong noise environment.

[0006] In a first aspect, the present invention provides a method for measuring the power frequency impedance of a line, comprising:

[0007] The injection point voltage signal and injection point current signal of the line are obtained according to the preset mixed test current signal, wherein the mixed test current signal is obtained by mixing the test current signals of each test frequency;

[0008] The injection point voltage signal and the injection point current signal are preprocessed respectively to obtain the target injection point voltage signal and the target injection point current signal;

[0009] According to the preset digital bandpass filter, the target injection point voltage sub-signals of each test frequency are separated from the target injection point voltage signal, and the target injection point current sub-signals of each test frequency are separated from the target injection point current signal.

[0010] According to the preset signal decomposition strategy, the voltage sub-signal and current sub-signal of each target injection point are decomposed by phase rotation. The average value of the decomposed components is used as the voltage fusion component corresponding to the voltage sub-signal of each target injection point and the current fusion component corresponding to the current sub-signal of each target injection point. The voltage fusion component includes a voltage fusion vertical component and a voltage fusion horizontal component, and the current fusion component includes a current fusion vertical component and a current fusion horizontal component.

[0011] The resistance and reactance values ​​at each frequency point are calculated based on the voltage and current fusion components, and resistance-frequency and reactance-frequency curves are generated based on the signal quality at each frequency point.

[0012] Read the power frequency resistance value and power frequency reactance value in the power frequency neighborhood of the resistance-frequency curve and the reactance-frequency curve, respectively.

[0013] Secondly, the present invention provides a line power frequency impedance measurement system, comprising:

[0014] The acquisition module is configured to acquire the injection point voltage signal and injection point current signal of the line according to a preset mixed test current signal, wherein the mixed test current signal is obtained by mixing test current signals of various test frequencies;

[0015] The preprocessing module is configured to preprocess the injection point voltage signal and the injection point current signal respectively to obtain the target injection point voltage signal and the target injection point current signal;

[0016] The selected module is configured to separate the target injection point voltage sub-signals of each test frequency from the target injection point voltage signal and the target injection point current sub-signals of each test frequency from the target injection point current signal according to a preset digital bandpass filter.

[0017] The decomposition module is configured to perform phase rotation decomposition on the voltage sub-signal and current sub-signal of each target injection point according to a preset signal decomposition strategy, and take the average value of the decomposed components as the voltage fusion component corresponding to the voltage sub-signal of each target injection point and the current fusion component corresponding to the current sub-signal of each target injection point. The voltage fusion component includes a voltage fusion vertical component and a voltage fusion horizontal component, and the current fusion component includes a current fusion vertical component and a current fusion horizontal component.

[0018] The generation module is configured to calculate the resistance and reactance values ​​at each frequency point based on each voltage fusion component and each current fusion component, and generate resistance-frequency curves and reactance-frequency curves based on the signal quality at each frequency point.

[0019] The reading module is configured to read the power frequency resistance value and the power frequency reactance value in the power frequency neighborhood of the resistance-frequency curve and the reactance-frequency curve, respectively.

[0020] Thirdly, an electronic device is provided, comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the steps of the line power frequency impedance measurement method according to any embodiment of the present invention.

[0021] Fourthly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor performs the steps of the line power frequency impedance measurement method according to any embodiment of the present invention.

[0022] The line power frequency impedance measurement method and system of this application effectively avoids power frequency interference by combining multi-frequency hybrid injection with digital bandpass filtering separation; further, it adopts phase rotation decomposition and fusion technology to orthogonally decompose the voltage / current sub-signals at each frequency point along multiple directional angles and fuse the average value, which significantly suppresses random noise and asynchronous component interference. The resistance / reactance calculation formula is constructed based on the fused components, which mathematically cancels the orthogonal error, making the calculation results closer to the true value and improving the measurement accuracy. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A flowchart of a line power frequency impedance measurement method provided in an embodiment of the present invention;

[0025] Figure 2 This is a structural block diagram of a line power frequency impedance measurement system provided in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Please see Figure 1 The diagram shows a flowchart of a line power frequency impedance measurement method according to this application.

[0029] like Figure 1 As shown, the method for measuring the power frequency impedance of a line specifically includes the following steps:

[0030] Step S101: Obtain the injection point voltage signal and injection point current signal of the line according to the preset mixed test current signal, wherein the mixed test current signal is obtained by mixing the test current signals of each test frequency.

[0031] In this step, at least three test current signals with different test frequencies are mixed into a mixed test current signal according to a preset ratio, and injected into the beginning of the line at the zero-crossing point of the power frequency voltage. The frequency value of the test frequency is not an integer multiple of the power frequency value. The injection point voltage signal and the injection point current signal of the line at the injection point are obtained.

[0032] Specifically, assuming the power frequency is 50Hz, the test frequency cannot be 100Hz, 150Hz, or 500Hz.

[0033] Step S102: Preprocess the injection point voltage signal and the injection point current signal respectively to obtain the target injection point voltage signal and the target injection point current signal.

[0034] Step S103: According to the preset digital bandpass filter, separate the target injection point voltage sub-signals of each test frequency from the target injection point voltage signal, and separate the target injection point current sub-signals of each test frequency from the target injection point current signal.

[0035] Step S104: According to the preset signal decomposition strategy, the voltage sub-signal and current sub-signal of each target injection point are decomposed by phase rotation, and the average value of the decomposed components is used as the voltage fusion component corresponding to the voltage sub-signal of each target injection point and the current fusion component corresponding to the current sub-signal of each target injection point. The voltage fusion component includes a voltage fusion vertical component and a voltage fusion horizontal component, and the current fusion component includes a current fusion vertical component and a current fusion horizontal component.

[0036] In this step, the voltage sub-signal of a target injection point is orthogonally decomposed along at least one preset direction angle to obtain a horizontal voltage component and a vertical voltage component corresponding to the at least one direction angle; the average value of each horizontal voltage component is calculated to obtain a voltage fusion horizontal component corresponding to the voltage sub-signal of the target injection point, and the average value of each vertical voltage component is calculated to obtain a voltage fusion vertical component corresponding to the voltage sub-signal of the target injection point; the current sub-signal of a target injection point is orthogonally decomposed along at least one preset direction angle to obtain a horizontal current component and a vertical current component corresponding to the at least one direction angle; the average value of each horizontal current component is calculated to obtain a current fusion horizontal component corresponding to the current sub-signal of the target injection point, and the average value of each vertical current component is calculated to obtain a current fusion vertical component corresponding to the current sub-signal of the target injection point.

[0037] Step S105: Calculate the resistance and reactance values ​​at each frequency point based on the voltage fusion component and the current fusion component, and generate resistance-frequency curves and reactance-frequency curves based on the signal quality at each frequency point.

[0038] In this step, the expression for calculating the resistance value at each frequency point is:

[0039] ;

[0040] In the formula, The resistance value at the k-th frequency point. For the voltage fusion level component at the k-th frequency point, For the current fusion horizontal component at the k-th frequency point, For the voltage vertical component at the k-th frequency point, The vertical component of the current at the k-th frequency point is fused.

[0041] The expression for calculating the reactance value at each frequency point is:

[0042] ;

[0043] In the formula, Let be the reactance value at the k-th frequency point.

[0044] Further, the signal quality at each frequency point is calculated, where the signal quality is the ratio of the absolute value of the target frequency intensity to the absolute value of the maximum neighboring interference intensity, the target frequency intensity is the amplitude of the test frequency corresponding to the frequency point, and the maximum neighboring interference intensity is the maximum amplitude within a ±5Hz frequency band centered on the test frequency, excluding the test frequency. At least one frequency point with a signal quality greater than a preset quality threshold is defined as a first target frequency point. At least one first target frequency point and the corresponding resistance value are input into a preset first two-dimensional coordinate system, and a first resistance-frequency curve is obtained by fitting. In the first two-dimensional coordinate system, the test frequency value corresponding to each frequency point is on the horizontal axis, and the resistance value corresponding to each frequency point is on the vertical axis. A sliding window of a preset size slides on the first resistance-frequency curve, and the first resistance-frequency curve is corrected according to at least one first target coordinate point in the sliding window to obtain the final resistance-frequency curve. At least one first target frequency point and the reactance value corresponding to the at least one first target frequency point are input into a preset second two-dimensional coordinate system to fit the first reactance-frequency curve. In the second two-dimensional coordinate system, the test frequency value corresponding to each frequency point is the abscissa, and the reactance value corresponding to each frequency point is the ordinate. A sliding window of a preset size slides on the first reactance-frequency curve, and the first reactance-frequency curve is corrected according to at least one second target coordinate point in the sliding window to obtain the final reactance-frequency curve.

[0045] In this embodiment, during actual measurements, due to background noise from the power grid, harmonic interference, or signal distortion, the impedance calculation results at certain frequency points may exhibit significant jumps or deviate from the true trend. A sliding window moves point by point on the curve, dynamically analyzing the changing characteristics of local data points (e.g., calculating the degree of coordinate change and comparing it with adjacent points). If the degree of change at a point exceeds the dynamic range determined by neighboring points, that point is identified as an anomaly and excluded (not included in the target coordinate point). This process effectively suppresses the influence of occasional interference on the overall curve shape and avoids misleading power frequency impedance readings due to outliers.

[0046] It should be noted that a sliding window of a preset size slides on the first resistance-frequency curve, and the first resistance-frequency curve is corrected based on at least one first target coordinate point in the sliding window to obtain the final resistance-frequency curve, which includes:

[0047] Obtain each first coordinate point in the current sliding window and calculate the degree of change of the first coordinate of each first coordinate point. The degree of change of the first coordinate is the ratio of the test frequency value to the resistance value of the same first coordinate point. The first coordinate point is a coordinate point in the first two-dimensional coordinate system. Determine whether the degree of change of a certain first coordinate of a certain first coordinate point is within the preset dynamic coordinate change range. The upper and lower limits of the dynamic coordinate change range are the degree of change of the first coordinates of two first coordinate points adjacent to a certain first coordinate point. If it is within the preset dynamic coordinate change range, then the certain first coordinate point is defined as the first target coordinate point; otherwise, the certain first coordinate point is not defined as the first target coordinate point. Correct the first resistance-frequency curve based on all the first target coordinate points to obtain the final resistance-frequency curve.

[0048] The process of correcting the first resistance-frequency curve based on all the first target coordinate points to obtain the final resistance-frequency curve means that a completely new, smooth resistance-frequency curve is refitted based on all the first target coordinate points to replace the first resistance-frequency curve containing outliers.

[0049] In one specific embodiment, the sliding window is a circular window with a preset radius, and the center of the circular window slides along the first resistance-frequency curve.

[0050] Set the sliding window size to 3 (i.e., analyze 3 consecutive coordinate points each time).

[0051] Slide the window from low frequency to high frequency.

[0052] First slide: The window contains points A(45, 10.2), B(47, 10.5), and C(49, 15.0);

[0053] Calculate the degree of change in the first coordinate of each point within the calculation window:

[0054] For point A(45, 10.2): the degree of change of the first coordinate a = 45 / 10.2≈4.412;

[0055] For point B (47, 10.5): the degree of change of the first coordinate is b = 47 / 10.5 ≈ 4.476;

[0056] For point C(49, 15.0): the degree of change of the first coordinate c = 49 / 15.0 ≈ 3.267;

[0057] For point B (47, 10.5), we determine that its left neighbor is A, with a change of approximately 4.412, and its right neighbor is C, with a change of approximately 3.267. Therefore, the range of dynamic coordinate change for point B is [3.267, 4.412] (the lower limit is the smaller of the left and right neighboring values, and the upper limit is the larger value).

[0058] Since the degree of change of point B itself is approximately 4.476, which is outside the range of dynamic coordinate change, point B is considered a point near the anomaly point. However, since the degree of change of point B itself slightly exceeds the limit, point B is not defined as the first target coordinate point.

[0059] Similarly, the process of sliding a window of a preset size on the first reactance-frequency curve and correcting the first reactance-frequency curve based on at least one second target coordinate point in the sliding window to obtain the final reactance-frequency curve includes: acquiring each second coordinate point in the current sliding window and calculating the degree of change of the second coordinate of each second coordinate point, where the degree of change of the second coordinate is the ratio of the test frequency value to the reactance value of the same second coordinate point, and the second coordinate point is a coordinate point in a second two-dimensional coordinate system; determining whether the degree of change of a certain second coordinate of a certain second coordinate point is within a preset dynamic coordinate change range, where the upper and lower limits of the dynamic coordinate change range are the degree of change of the second coordinates of two second coordinate points adjacent to a certain second coordinate point; if it is within the preset dynamic coordinate change range, then a certain second coordinate point is defined as a second target coordinate point, otherwise a certain second coordinate point is not defined as a second target coordinate point; and correcting the first reactance-frequency curve based on all second target coordinate points to obtain the final reactance-frequency curve.

[0060] Step S106: Read the power frequency resistance value and power frequency reactance value in the power frequency neighborhood of the resistance-frequency curve and the reactance-frequency curve, respectively.

[0061] In summary, the method of this application effectively avoids power frequency interference by combining multi-frequency hybrid injection (non-integer multiples of the power frequency) with digital bandpass filtering separation; furthermore, it adopts phase rotation decomposition and fusion technology to orthogonally decompose the voltage / current sub-signals at each frequency point along multiple directional angles and fuse the average value, which significantly suppresses random noise and asynchronous component interference. The resistance / reactance calculation formula is constructed based on the fused components, which mathematically cancels the orthogonal error, making the calculation results closer to the true value and improving the measurement accuracy.

[0062] Please see Figure 2 The diagram shows a structural block diagram of a line power frequency impedance measurement system according to this application.

[0063] like Figure 2As shown, the line power frequency impedance measurement system 200 includes an acquisition module 210, a preprocessing module 220, a selection module 230, a decomposition module 240, a generation module 250, and a reading module 260.

[0064] The acquisition module 210 is configured to acquire the injection point voltage signal and injection point current signal of the line according to a preset mixed test current signal, wherein the mixed test current signal is obtained by mixing test current signals of various test frequencies; the preprocessing module 220 is configured to preprocess the injection point voltage signal and the injection point current signal respectively to obtain the target injection point voltage signal and the target injection point current signal; the selection module 230 is configured to separate the target injection point voltage sub-signals of various test frequencies from the target injection point voltage signal and the target injection point current sub-signals of various test frequencies from the target injection point current signal according to a preset digital bandpass filter; the decomposition module 240 is configured to decompose the target injection point voltage sub-signals and the target injection point current sub-signals of various test frequencies according to a preset signal decomposition strategy. Each target injection point current sub-signal is phase-rotated and decomposed. The average value of the decomposed components is used as the voltage fusion component corresponding to the voltage sub-signal of each target injection point, and the current fusion component corresponding to the current sub-signal of each target injection point. The voltage fusion component includes a voltage fusion vertical component and a voltage fusion horizontal component, and the current fusion component includes a current fusion vertical component and a current fusion horizontal component. The generation module 250 is configured to calculate the resistance and reactance values ​​at each frequency point based on each voltage fusion component and each current fusion component, and generate resistance-frequency curves and reactance-frequency curves based on the signal quality at each frequency point. The reading module 260 is configured to read the power frequency resistance value and power frequency reactance value in the power frequency neighborhood of the resistance-frequency curve and the reactance-frequency curve, respectively.

[0065] It should be understood that Figure 2 The modules and references described in the document Figure 1 The steps described in the text correspond to those in the method described above. Therefore, the operations, features, and corresponding technical effects described above also apply to the method described in the text. Figure 2 The various modules in the document will not be described in detail here.

[0066] In other embodiments, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor performs the line power frequency impedance measurement method in any of the above method embodiments.

[0067] In one embodiment, the computer-readable storage medium of the present invention stores computer-executable instructions, which are configured as follows:

[0068] The injection point voltage signal and injection point current signal of the line are obtained according to the preset mixed test current signal, wherein the mixed test current signal is obtained by mixing the test current signals of each test frequency;

[0069] The injection point voltage signal and the injection point current signal are preprocessed respectively to obtain the target injection point voltage signal and the target injection point current signal;

[0070] According to the preset digital bandpass filter, the target injection point voltage sub-signals of each test frequency are separated from the target injection point voltage signal, and the target injection point current sub-signals of each test frequency are separated from the target injection point current signal.

[0071] According to the preset signal decomposition strategy, the voltage sub-signal and current sub-signal of each target injection point are decomposed by phase rotation. The average value of the decomposed components is used as the voltage fusion component corresponding to the voltage sub-signal of each target injection point and the current fusion component corresponding to the current sub-signal of each target injection point. The voltage fusion component includes a voltage fusion vertical component and a voltage fusion horizontal component, and the current fusion component includes a current fusion vertical component and a current fusion horizontal component.

[0072] The resistance and reactance values ​​at each frequency point are calculated based on the voltage and current fusion components, and resistance-frequency and reactance-frequency curves are generated based on the signal quality at each frequency point.

[0073] Read the power frequency resistance value and power frequency reactance value in the power frequency neighborhood of the resistance-frequency curve and the reactance-frequency curve, respectively.

[0074] Computer-readable storage media may include a stored program area and a stored data area, wherein the stored program area may store an operating system and an application program required for at least one function; the stored data area may store data created based on the use of the line frequency impedance measurement system, etc. Furthermore, the computer-readable storage medium may include high-speed random access memory, and may also include memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, the computer-readable storage medium may optionally include memory remotely configured relative to a processor, and this remote memory may be connected to the line frequency impedance measurement system via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0075] Figure 3 This is a schematic diagram of the structure of the electronic device provided in the embodiment of the present invention, such as... Figure 3As shown, the device includes a processor 310 and a memory 320. The electronic device may also include an input device 330 and an output device 340. The processor 310, memory 320, input device 330, and output device 340 can be connected via a bus or other means. Figure 3 Taking a bus connection as an example, the memory 320 is the computer-readable storage medium described above. The processor 310 executes various server functions and data processing by running non-volatile software programs, instructions, and modules stored in the memory 320, thereby implementing the line power frequency impedance measurement method described in the above embodiment. The input device 330 can receive input digital or character information and generate key signal inputs related to user settings and function control of the line power frequency impedance measurement system. The output device 340 may include a display screen or other display device.

[0076] The aforementioned electronic device can execute the method provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the method provided in the embodiments of the present invention.

[0077] In one implementation, the above-described electronic device is applied in a line power frequency impedance measurement system for a client, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to:

[0078] The injection point voltage signal and injection point current signal of the line are obtained according to the preset mixed test current signal, wherein the mixed test current signal is obtained by mixing the test current signals of each test frequency;

[0079] The injection point voltage signal and the injection point current signal are preprocessed respectively to obtain the target injection point voltage signal and the target injection point current signal;

[0080] According to the preset digital bandpass filter, the target injection point voltage sub-signals of each test frequency are separated from the target injection point voltage signal, and the target injection point current sub-signals of each test frequency are separated from the target injection point current signal.

[0081] According to the preset signal decomposition strategy, the voltage sub-signal and current sub-signal of each target injection point are decomposed by phase rotation. The average value of the decomposed components is used as the voltage fusion component corresponding to the voltage sub-signal of each target injection point and the current fusion component corresponding to the current sub-signal of each target injection point. The voltage fusion component includes a voltage fusion vertical component and a voltage fusion horizontal component, and the current fusion component includes a current fusion vertical component and a current fusion horizontal component.

[0082] The resistance and reactance values ​​at each frequency point are calculated based on the voltage and current fusion components, and resistance-frequency and reactance-frequency curves are generated based on the signal quality at each frequency point.

[0083] Read the power frequency resistance value and power frequency reactance value in the power frequency neighborhood of the resistance-frequency curve and the reactance-frequency curve, respectively.

[0084] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of various embodiments or some parts of embodiments.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring the power frequency impedance of a power line, characterized in that, include: The injection point voltage signal and injection point current signal of the line are obtained according to the preset mixed test current signal, wherein the mixed test current signal is obtained by mixing the test current signals of each test frequency; The injection point voltage signal and the injection point current signal are preprocessed respectively to obtain the target injection point voltage signal and the target injection point current signal; According to the preset digital bandpass filter, the target injection point voltage sub-signals of each test frequency are separated from the target injection point voltage signal, and the target injection point current sub-signals of each test frequency are separated from the target injection point current signal. According to the preset signal decomposition strategy, the voltage sub-signal and current sub-signal of each target injection point are decomposed by phase rotation. The average value of the decomposed components is used as the voltage fusion component corresponding to the voltage sub-signal of each target injection point and the current fusion component corresponding to the current sub-signal of each target injection point. The voltage fusion component includes a voltage fusion vertical component and a voltage fusion horizontal component, and the current fusion component includes a current fusion vertical component and a current fusion horizontal component. The resistance and reactance values ​​at each frequency point are calculated based on the voltage and current fusion components, and resistance-frequency and reactance-frequency curves are generated based on the signal quality at each frequency point. Read the power frequency resistance value and power frequency reactance value in the power frequency neighborhood of the resistance-frequency curve and the reactance-frequency curve, respectively.

2. The method for measuring power frequency impedance of a line according to claim 1, characterized in that, The step of obtaining the injection point voltage signal and injection point current signal of the line based on the preset mixed test current signal includes: At least three test current signals with different test frequencies are mixed into a mixed test current signal according to a preset ratio and injected into the beginning of the line at the zero crossing point of the power frequency voltage. The frequency value of the test frequency is not an integer multiple of the frequency value of the power frequency. Obtain the injection point voltage signal and injection point current signal of the line at the injection point.

3. The method for measuring power frequency impedance of a line according to claim 1, characterized in that, The step of performing phase rotation decomposition on the voltage sub-signal and current sub-signal of each target injection point according to a preset signal decomposition strategy, and taking the average value of the decomposed components as the voltage fusion component corresponding to each target injection point voltage sub-signal, and the current fusion component corresponding to each target injection point current sub-signal, includes: The voltage sub-signal of a target injection point is orthogonally decomposed along at least one preset direction angle to obtain the horizontal voltage component and the vertical voltage component corresponding to the at least one direction angle. The average value of each horizontal voltage component is calculated to obtain a voltage fusion horizontal component corresponding to the voltage sub-signal of the target injection point; and the average value of each vertical voltage component is calculated to obtain a voltage fusion vertical component corresponding to the voltage sub-signal of the target injection point. The current sub-signal of a target injection point is orthogonally decomposed along at least one preset direction angle to obtain the horizontal current component and the vertical current component corresponding to the at least one direction angle. The average value of each horizontal current component is calculated to obtain a current fusion horizontal component corresponding to the current sub-signal of the target injection point. The average value of each vertical current component is calculated to obtain a current fusion vertical component corresponding to the current sub-signal of the target injection point.

4. The method for measuring power frequency impedance of a line according to claim 1, characterized in that, The expression for calculating the resistance value at each frequency point is: ； In the formula, The resistance value at the k-th frequency point. For the voltage fusion level component at the k-th frequency point, For the current fusion horizontal component at the k-th frequency point, For the voltage vertical component at the k-th frequency point, The vertical component of the current at the k-th frequency point is fused. The expression for calculating the reactance value at each frequency point is: ； In the formula, Let be the reactance value at the k-th frequency point.

5. The method for measuring power frequency impedance of a line according to claim 1, characterized in that, The process of calculating the resistance and reactance values ​​at each frequency point based on the fused voltage and current components, and generating resistance-frequency and reactance-frequency curves based on the signal quality at each frequency point, includes: Calculate the signal quality at each frequency point, where the signal quality is the ratio of the absolute value of the target frequency intensity to the absolute value of the maximum neighboring interference intensity, the target frequency intensity is the amplitude of the test frequency corresponding to the frequency point, and the maximum neighboring interference intensity is the maximum amplitude excluding the test frequency within the ±5Hz frequency band centered on the test frequency. The first target frequency point is defined as at least one frequency point whose signal quality is greater than a preset quality threshold. At least one first target frequency point and the resistance value corresponding to the at least one first target frequency point are input into a preset first two-dimensional coordinate system to fit a first resistance-frequency curve, wherein the test frequency value corresponding to each frequency point is the abscissa and the resistance value corresponding to each frequency point is the ordinate in the first two-dimensional coordinate system. A sliding window of a preset size slides on the first resistance-frequency curve, and the first resistance-frequency curve is corrected according to at least one first target coordinate point in the sliding window to obtain the final resistance-frequency curve. At least one first target frequency point and the reactance value corresponding to the at least one first target frequency point are input into a preset second two-dimensional coordinate system to obtain a first reactance-frequency curve. In the second two-dimensional coordinate system, the test frequency value corresponding to each frequency point is the abscissa and the reactance value corresponding to each frequency point is the ordinate. A sliding window of a preset size slides on the first reactance-frequency curve, and the first reactance-frequency curve is corrected according to at least one second target coordinate point in the sliding window to obtain the final reactance-frequency curve.

6. The method for measuring power frequency impedance of a line according to claim 5, characterized in that, The sliding window based on a preset size slides on the first resistance-frequency curve, and the first resistance-frequency curve is corrected according to at least one first target coordinate point in the sliding window to obtain the final resistance-frequency curve, including: Obtain each first coordinate point in the current sliding window and calculate the degree of change of the first coordinate of each first coordinate point. The degree of change of the first coordinate is the ratio of the test frequency value to the resistance value of the same first coordinate point. The first coordinate point is the coordinate point in the first two-dimensional coordinate system. Determine whether the degree of change of a certain first coordinate of a certain first coordinate point is within a preset range of dynamic coordinate change, wherein the upper and lower limits of the range of dynamic coordinate change are the degree of change of the first coordinates of two first coordinate points adjacent to the certain first coordinate point; If the change is within the preset range of dynamic coordinates, then the first coordinate point is defined as the first target coordinate point; otherwise, the first coordinate point is not defined as the first target coordinate point. The first resistance-frequency curve is corrected based on all the first target coordinate points to obtain the final resistance-frequency curve.

7. The method for measuring power frequency impedance of a line according to claim 5, characterized in that, The sliding window based on a preset size slides on the first reactance-frequency curve, and the first reactance-frequency curve is corrected according to at least one second target coordinate point in the sliding window to obtain the final reactance-frequency curve, including: Obtain each second coordinate point in the current sliding window and calculate the degree of change of the second coordinate of each second coordinate point. The degree of change of the second coordinate is the ratio of the test frequency value to the reactance value of the same second coordinate point. The second coordinate point is the coordinate point in the second two-dimensional coordinate system. Determine whether the degree of change of a certain second coordinate of a certain second coordinate point is within a preset range of dynamic coordinate change, wherein the upper and lower limits of the range of dynamic coordinate change are the degree of change of the second coordinates of two second coordinate points adjacent to the certain second coordinate point; If the dynamic coordinate change is within the preset range, then the second coordinate point is defined as the second target coordinate point; otherwise, the second coordinate point is not defined as the second target coordinate point. The first reactance-frequency curve is corrected based on all the second target coordinate points to obtain the final reactance-frequency curve.

8. A power frequency impedance measurement system for power lines, characterized in that, include: The acquisition module is configured to acquire the injection point voltage signal and injection point current signal of the line according to a preset mixed test current signal, wherein the mixed test current signal is obtained by mixing test current signals of various test frequencies; The preprocessing module is configured to preprocess the injection point voltage signal and the injection point current signal respectively to obtain the target injection point voltage signal and the target injection point current signal; The selected module is configured to separate the target injection point voltage sub-signals of each test frequency from the target injection point voltage signal and the target injection point current sub-signals of each test frequency from the target injection point current signal according to a preset digital bandpass filter. The decomposition module is configured to perform phase rotation decomposition on the voltage sub-signal and current sub-signal of each target injection point according to a preset signal decomposition strategy, and take the average value of the decomposed components as the voltage fusion component corresponding to the voltage sub-signal of each target injection point and the current fusion component corresponding to the current sub-signal of each target injection point. The voltage fusion component includes a voltage fusion vertical component and a voltage fusion horizontal component, and the current fusion component includes a current fusion vertical component and a current fusion horizontal component. The generation module is configured to calculate the resistance and reactance values ​​at each frequency point based on each voltage fusion component and each current fusion component, and generate resistance-frequency curves and reactance-frequency curves based on the signal quality at each frequency point. The reading module is configured to read the power frequency resistance value and the power frequency reactance value in the power frequency neighborhood of the resistance-frequency curve and the reactance-frequency curve, respectively.

9. An electronic device, characterized in that, include: At least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method according to any one of claims 1 to 7.

Images