Method, device, equipment and product for analyzing high-frequency impedance characteristics of grounding grid

Abstract

The application provides a method, device, equipment and product for analyzing high-frequency impedance characteristics of a grounding grid. A signal of an odd-symmetry bipolar trapezoidal wave is generated, the fundamental frequency of the signal is in a range of 1 kHz to 10 MHz, and the rising time of the signal is less than 200 ns. After the signal is amplified, the signal is injected into the grounding grid. Voltage and current signals of the grounding grid in response to the signal of the odd-symmetry bipolar trapezoidal wave are collected. The voltage and current signals are subjected to frequency domain conversion processing to obtain edge frequency domain components and flat-top frequency domain components. The impedance spectrum of the grounding grid is calculated according to the edge frequency domain components and the flat-top frequency domain components, and the high-frequency impedance characteristics are determined. The technical defects that existing excitation signals are difficult to cover the high-frequency band and the high-frequency detection precision is insufficient are solved, the precision of the analysis of the high-frequency impedance characteristics of the grounding grid and the fault tracing capability are improved, and the fine state evaluation requirement of the grounding grid under high-frequency transient working conditions is met.

Description

Technical Field

[0001] This application relates to the field of power safety technology, and in particular to a method, apparatus, equipment and product for analyzing the high-frequency impedance characteristics of grounding grids. Background Technology

[0002] In modern power systems, the grounding grid, as a core facility ensuring the safe operation of power equipment and the protection of personnel, directly affects the reliability and stability of the entire system. However, grounding grids buried deep in the soil for extended periods are susceptible to corrosion, breakage, and other natural factors, leading to a gradual deterioration in grounding performance. Therefore, there is an urgent need for a technical means to comprehensively analyze the impedance characteristics of the grounding grid over a wide frequency range (especially the high-frequency band) to achieve accurate assessment of the grounding grid's condition and early fault warning, thereby ensuring the safe and stable operation of the power system.

[0003] Existing techniques for analyzing the impedance characteristics of grounding grids mainly rely on the sinusoidal excitation method. This method involves injecting a single-frequency sinusoidal signal into the grounding grid and measuring its impedance response, thereby deriving the electrical parameters of the grounding grid.

[0004] However, the above analysis techniques cannot cover the high-frequency band of the grounding grid, which reduces the accuracy of the analysis of the grounding grid impedance characteristics. Summary of the Invention

[0005] This application provides a method, apparatus, equipment, and product for analyzing the high-frequency impedance characteristics of a grounding grid, in order to solve the technical problem that existing traditional sinusoidal excitation methods cannot capture the high-frequency impedance characteristics of grounding grids due to insufficient frequency coverage.

[0006] In a first aspect, this application provides a method for analyzing the high-frequency impedance characteristics of a grounding grid, including:

[0007] An odd-symmetric bipolar trapezoidal wave excitation signal is generated, wherein the fundamental frequency of the odd-symmetric bipolar trapezoidal wave excitation signal is in the range of 1 kHz to 10 MHz, and its rise time is less than 200 ns.

[0008] The odd-symmetric bipolar trapezoidal wave excitation signal is amplified and then injected into the grounding grid.

[0009] The voltage and current signals of the grounding grid in response to the odd-symmetric bipolar trapezoidal wave excitation signal are collected.

[0010] The voltage signal and the current signal are subjected to frequency domain conversion to obtain edge frequency domain components and flat-top frequency domain components;

[0011] The impedance spectrum of the grounding grid is calculated based on the edge frequency domain component and the flat-top frequency domain component to determine the high-frequency impedance characteristics.

[0012] Furthermore, an odd-symmetric bipolar trapezoidal wave excitation signal is generated, including:

[0013] Determine the bipolar trapezoidal wave signal generator;

[0014] Adjust the duty cycle of the bipolar trapezoidal wave signal generator to obtain the target fundamental frequency;

[0015] The target rise time is obtained by adjusting the rise time of the bipolar trapezoidal wave signal generator.

[0016] Based on the target fundamental frequency and the target rise time, an odd-symmetric bipolar trapezoidal wave excitation signal is generated.

[0017] Further, the voltage signal and the current signal are subjected to frequency domain transformation to obtain edge frequency domain components and flat-top frequency domain components, including:

[0018] The voltage signal and the current signal are preprocessed to obtain the target voltage signal and the target current signal;

[0019] The target voltage signal and the target current signal are subjected to frequency domain conversion to obtain a frequency domain signal;

[0020] Based on the time-domain segmentation interval of the trapezoidal wave, the edge frequency domain components corresponding to the rising and falling edges of the waveform and the flat-top frequency domain components corresponding to the flat-top segments of the waveform are extracted from the frequency domain signal.

[0021] Further, the odd-symmetric bipolar trapezoidal wave excitation signal is amplified and then injected into the grounding grid, including:

[0022] The odd-symmetric bipolar trapezoidal wave excitation signal is amplified using a power amplifier to obtain an amplified excitation signal.

[0023] The amplified excitation signal is coupled using a frequency conversion isolation transformer and then injected into the grounding grid.

[0024] Further, the voltage and current signals of the grounding grid in response to the odd-symmetric bipolar trapezoidal wave excitation signal are collected, including:

[0025] High-frequency voltage sensors and high-frequency current sensors are respectively arranged on multiple preset nodes of the grounding grid;

[0026] The voltage and current signals are acquired synchronously within each complete waveform cycle, wherein each complete waveform cycle includes all time-domain waveforms of the edge segment, the flat-top segment, the positive half-cycle, and the negative half-cycle.

[0027] The preset node includes at least one of the following: grounding grid edge, branch node, and preset corrosion risk area.

[0028] Further, based on the edge frequency domain component and the flat-top frequency domain component, the impedance spectrum of the grounding grid is calculated to determine the high-frequency impedance characteristics, including:

[0029] The edge impedance spectrum and the flat-top impedance spectrum are calculated based on the edge frequency domain component and the flat-top frequency domain component. The edge impedance spectrum is used to characterize the high-frequency propagation difference between the conductor and the connection node, and the flat-top impedance spectrum is used to characterize soil leakage and quasi-steady-state conduction state.

[0030] Extract the amplitude-frequency and phase-frequency characteristics of the edge impedance spectrum and the flat-top impedance spectrum;

[0031] The amplitude-frequency characteristic and the phase-frequency characteristic are fused to obtain the complete impedance spectrum of the grounding grid, and the high-frequency impedance characteristics are determined.

[0032] Further, after calculating the impedance spectrum of the grounding grid based on the edge frequency domain component and the flat-top frequency domain component, and determining the high-frequency impedance characteristics, the method further includes:

[0033] Collect the physical geometric parameters of the grounding grid and the electrical parameters of the soil;

[0034] Based on the physical geometric parameters and the soil electrical parameters, a theoretical model of the distributed parameters of the grounding grid is constructed;

[0035] Based on the theoretical model of the distributed parameters of the grounding grid, the theoretical impedance spectrum of the grounding grid is calculated.

[0036] The operating status of the grounding grid is obtained by comparing the theoretical impedance spectrum with the calculated impedance spectrum of the grounding grid.

[0037] Secondly, this application provides an analysis device for the high-frequency impedance characteristics of a grounding grid, comprising:

[0038] An excitation signal generation module is used to generate an odd-symmetric bipolar trapezoidal wave excitation signal, wherein the fundamental frequency of the odd-symmetric bipolar trapezoidal wave excitation signal is in the range of 1 kHz to 10 MHz and its rise time is less than 200 ns.

[0039] The signal injection module is used to amplify the odd-symmetric bipolar trapezoidal wave excitation signal and then inject it into the grounding grid.

[0040] The signal acquisition module is used to acquire the voltage and current signals of the grounding grid in response to the odd-symmetric bipolar trapezoidal wave excitation signal;

[0041] The frequency domain conversion module is used to perform frequency domain conversion processing on the voltage signal and the current signal to obtain edge frequency domain components and flat-top frequency domain components.

[0042] The impedance characteristic determination module is used to calculate the impedance spectrum of the grounding grid based on the edge frequency domain component and the flat-top frequency domain component, and to determine the high-frequency impedance characteristics.

[0043] Fourthly, this application provides an analysis device for the high-frequency impedance characteristics of a grounding grid, comprising: a memory and a processor;

[0044] The memory stores computer-executed instructions;

[0045] The processor executes computer execution instructions stored in the memory, causing the processor to perform the method as described in any of the first aspects.

[0046] Fourthly, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the first aspect and / or various possible implementations of the first aspect.

[0047] This application provides a method, apparatus, equipment, and product for analyzing the high-frequency impedance characteristics of a grounding grid. It generates an odd-symmetric bipolar trapezoidal wave excitation signal with a fundamental frequency in the range of 1 kHz to 10 MHz and a rise time of less than 200 ns. The excitation signal is amplified and then injected into the grounding grid. Voltage and current signals from the grounding grid in response to the excitation signal are collected. Frequency domain transformation is performed on the voltage and current signals to obtain edge and flat-top frequency domain components. Based on these components, the impedance spectrum of the grounding grid is calculated to determine the high-frequency impedance characteristics. This method overcomes the technical shortcomings of existing excitation signals, such as difficulty in covering high-frequency bands and insufficient high-frequency detection accuracy. It improves the accuracy of high-frequency impedance characteristic analysis and fault tracing capabilities of grounding grids, and fulfills the requirement for refined condition assessment of grounding grids under high-frequency transient conditions. Attached Figure Description

[0048] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0049] Figure 1 A flowchart illustrating an embodiment of the method for analyzing the high-frequency impedance characteristics of the grounding grid provided in this application;

[0050] Figure 2 A schematic flowchart of Embodiment 2 of the method for analyzing the high-frequency impedance characteristics of the grounding grid provided in this application;

[0051] Figure 3 A flowchart illustrating Embodiment 3 of the method for analyzing the high-frequency impedance characteristics of the grounding grid provided in this application;

[0052] Figure 4 A schematic diagram of the bipolar trapezoidal wave excitation provided in this application;

[0053] Figure 5 Experimental results of the method for analyzing the high-frequency impedance characteristics of the grounding grid provided in this application are shown in the figure.

[0054] Figure 6 A schematic diagram of the structure of the analysis device for the high-frequency impedance characteristics of the grounding grid provided in this application;

[0055] Figure 7 A schematic diagram of the structure of the analysis device for the high-frequency impedance characteristics of the grounding grid provided in this application.

[0056] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0057] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0058] This application applies to the condition assessment and fault diagnosis of grounding grids in scenarios such as large substations and transmission line hubs in power systems. Under the impact of high-frequency transient currents such as lightning strikes and switching overvoltages, the grounding grid needs to conduct current quickly and maintain stable performance. However, grounding grids buried deep in the soil for a long time are prone to performance degradation due to corrosion, breakage, and other problems. Traditional detection methods are difficult to cover high-frequency characteristics and cannot detect local defects in a timely manner, resulting in significant lag in fault diagnosis.

[0059] Based on the above scenarios, it can be seen that the existing technical solutions (such as the sinusoidal wave sweep frequency method and the even-symmetric triangular wave excitation detection method) have the following technical problems: (1) The sinusoidal wave sweep frequency requires point-by-point measurement, which is inefficient and cannot cover the high-frequency band (>50MHz), resulting in the lack of high-frequency characteristic analysis. (2) The lumped parameter model (such as the RLC equivalent circuit) ignores the effect of the grounding grid distributed parameters (such as the skin effect) and cannot reflect the difference in impedance distribution in the plane, resulting in model distortion. (3) The sinusoidal signal has a low signal-to-noise ratio in the high-frequency band and is easily affected by environmental noise, resulting in a decrease in measurement accuracy. (4) The existing methods only focus on the impedance modulus value and do not combine phase information, so they cannot achieve high-sensitivity detection of conductor defects through the amplitude-frequency and phase-frequency dual-dimensional characteristics. For example, in the lightning strike scenario, the grounding grid needs to quickly conduct high-frequency current, but the traditional method cannot capture the changes in high-frequency parameters, resulting in a delay in fault diagnosis, which may cause equipment damage or personal safety accidents.

[0060] Based on the aforementioned technical problems, this application addresses the urgent need for high-frequency characteristic analysis of power grid grounding systems. First, it identifies the limitations of traditional sinusoidal wave excitation and the dual limitations of even-symmetric triangular wave excitation (insufficient frequency coverage and errors due to model simplification): sinusoidal waves suffer from insufficient frequency coverage and low detection efficiency, while even-symmetric triangular waves lack segmentation characteristics, cannot decouple multi-source defects, and have poor model adaptability. To address the need for high-frequency characteristic analysis, this application proposes using an odd-symmetric bipolar trapezoidal wave excitation signal as a dedicated broadband excitation source. Leveraging the natural segmentation characteristics of its steep waveform edges enriching high-frequency harmonics and its smooth, flat-topped segment adapting to mid-to-low frequency steady-state responses, it achieves full-coverage detection across a wide frequency range from power frequency to tens of MHz, while simultaneously decoupling the high-frequency response of the grounding grid conductor from the soil's steady-state current dissipation response. Furthermore, it dynamically calculates grounding grid resistance, inductance, and other parameters using a distributed parameter model, and extracts the amplitude-phase frequency characteristics of the impedance spectrum through signal processing techniques. Finally, by comparing the frequency domain deviation between the measured impedance spectrum and the theoretical model, it achieves accurate identification and defect location of the non-uniform impedance distribution within the grounding grid plane. This technical approach overcomes the problems of model simplification and functional limitation in existing technologies, providing a comprehensive and high-precision solution for grounding grid status assessment.

[0061] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0062] Figure 1 This is a flowchart illustrating an embodiment of the method for analyzing the high-frequency impedance characteristics of the grounding grid provided in this application. Figure 1 As shown, the method includes:

[0063] S101, Generate an odd-symmetric bipolar trapezoidal wave excitation signal.

[0064] Among them, the odd-symmetric bipolar trapezoidal wave excitation signal is a periodic non-sinusoidal voltage or current waveform. Each cycle consists of a fast rising edge, a flat-top segment, a fast falling edge (with opposite polarities), and a negative flat-top segment. The waveform is symmetrical about the time axis (odd-symmetric) and has no DC component. Its Fourier series expansion contains the fundamental wave and abundant odd harmonics, with a regular spectral distribution and strong controllability.

[0065] In this application, the fundamental frequency of the bipolar trapezoidal wave excitation signal is set in the range of 1 kHz to 10 MHz, and its rise time is less than 200 ns. The fundamental frequency refers to the repetition frequency of the periodic waveform itself, which is the lowest frequency among the harmonic components. The rise time refers to the time required for the signal to rise from 10% to 90% of its amplitude, and is a key parameter for measuring the steepness of the signal edge. The shorter the rise time, the richer the high-frequency harmonic components contained in the signal, which can fully stimulate the high-frequency skin effect and distributed parameter response characteristics of the grounding grid, and accurately match high-frequency transient conditions such as lightning strikes and switching overvoltages.

[0066] This step aims to generate an excitation source with controllable spectral characteristics suitable for exciting a wideband response of the grounding grid. Specifically, it includes: (1) determining a bipolar trapezoidal wave signal generator. For example, an arbitrary waveform generator or a dedicated trapezoidal wave generator with adjustable waveform parameters is selected as the signal source. (2) adjusting the duty cycle of the bipolar trapezoidal wave signal generator to obtain the target fundamental frequency. Specifically, the duty cycle refers to the ratio of the peak time to half a period. By adjusting the duty cycle and period, the target fundamental frequency can be set. In this application, the fundamental frequency is set in the range of 1kHz to 10MHz so that its harmonics can effectively cover the high-frequency transient current band (such as the main spectrum of lightning waves and switching overvoltages) from near the power frequency to tens of MHz. (3) adjusting the rise time of the bipolar trapezoidal wave signal generator and strictly controlling the signal rise time to within 200ns to obtain the target rise time. Specifically, according to the Fourier analysis principle, the steepness of the signal edge determines the content of its high-frequency harmonics. That is, the shorter the rise time, the richer the high-frequency components of the signal and the stronger the energy. (4) Generate a standard distortion-free odd-symmetric bipolar trapezoidal wave excitation signal based on the target fundamental frequency and the target rise time.

[0067] This step achieves a wide-bandwidth excitation effect with a single excitation, greatly improving testing efficiency. More importantly, the odd-symmetric waveform structure used in this application can completely eliminate DC bias interference. At the same time, by flexibly adjusting the rise time and duty cycle, the high-frequency harmonic energy distribution can be precisely controlled. This allows for the targeted capture of subtle changes in high-frequency parameters caused by the conductor skin effect, providing a dedicated waveform foundation for subsequent edge and flat-top segmented frequency domain analysis and dual impedance spectrum splitting calculations. This solves the technical problems of traditional sinusoidal waves having narrow frequency band coverage, insufficient high-frequency energy of ordinary even-symmetric triangular waves, lack of segmentation characteristics, and inability to distinguish detection targets.

[0068] S102. After amplifying the odd-symmetric bipolar trapezoidal wave excitation signal, it is injected into the grounding grid.

[0069] This step aims to safely and effectively apply the generated odd-symmetric bipolar trapezoidal wave excitation signal to the grounding grid under test, fully preserving the high-frequency edges and mid-to-low-frequency flat-top characteristics of the waveform, providing a reliable excitation input for subsequent high-precision signal analysis. Specifically, this step uses a power amplifier to amplify the low-power odd-symmetric bipolar trapezoidal wave excitation signal output from the signal generator to a high-power signal sufficient to generate a measurable response in the grounding grid. A frequency conversion isolation transformer adapted to the 1kHz~10MHz frequency band is used to couple the amplified excitation signal to the grounding grid, simultaneously achieving electrical isolation between the measurement system and the grounding grid to prevent ground potential rise from damaging the measurement equipment, and ensuring attenuation-free and distortion-free transmission of the signal across the entire 1kHz~10MHz frequency band.

[0070] The frequency conversion isolation transformer selected in this step features ultra-wide bandwidth and low-distortion transmission characteristics, effectively avoiding the defects of high-frequency signal attenuation and waveform distortion in traditional coupling equipment, and fully preserving the ultra-high frequency harmonics carried by the steep edges of the trapezoidal wave and the mid-to-low frequency steady-state signal characteristics carried by the flat-top section. Simultaneously, the electrical isolation design effectively isolates interference and equipment damage risks caused by sudden rises in ground potential of the grounding grid, ensuring the safe operation of the testing system.

[0071] For example, the odd-symmetric bipolar trapezoidal wave excitation signal generated by S101 is input to a power amplifier. Depending on the size of the grounding grid and the soil resistivity, the signal is amplified to a suitable voltage amplitude (e.g., 50V-500V) to ensure the generated response signal has a sufficient signal-to-noise ratio without damaging the grounding grid or connected equipment. The amplified excitation signal is then coupled to a designated injection point in the grounding grid (typically a grounding down conductor or an easily accessible grounding point) via a high-frequency isolation transformer. This transformer has wide bandwidth characteristics (e.g., covering 10kHz-100MHz) and can transmit the ultra-high frequency harmonics carried by the steep edges of the trapezoidal wave and the mid-to-low frequency steady-state signals carried by the flat-top section with minimal distortion.

[0072] This step ensures that the odd-symmetric bipolar trapezoidal wave excitation signal and the flat-top full-dimensional waveform characteristics are fully injected into the grounding grid, overcoming the signal attenuation and distortion problems caused by improper coupling at high frequencies in traditional methods. The use of a high-frequency isolation transformer not only ensures safety but also maintains the wide bandwidth and high edge characteristics of the excitation signal, enabling the subsequent acquisition of response signals that accurately reflect the high-frequency characteristics of the grounding grid, laying the foundation for accurate analysis of high-frequency impedance characteristics.

[0073] S103. Collect the voltage and current signals of the grounding grid in response to the odd-symmetric bipolar trapezoidal wave excitation signal.

[0074] This step aims to comprehensively acquire the spatial response signal of the grounding grid under broadband excitation. To achieve accurate analysis of the impedance distribution in the grounding grid plane, multiple sets of high-frequency voltage and current sensors are deployed to form a distributed acquisition network, completely preserving full-cycle waveform data adapted for segmented frequency domain analysis.

[0075] By calculating the impedance spectrum differences at each sensor location (such as the amplitude-frequency / phase-frequency characteristic deviations in the lateral and longitudinal directions), a planar impedance difference map is constructed. Combining the broadband characteristics of odd-symmetric bipolar trapezoidal wave excitation, the frequency domain deviation between the measured impedance spectrum and the theoretical model is analyzed to infer the spatial location of the defect. For example, corrosion defects may cause a high-frequency impedance surge in a local area, while fracture defects may exhibit phase reversals at multiple sensor locations. Spatial response modeling significantly improves the resolution of defect localization and avoids localization errors caused by the limitations of a single sensor location.

[0076] Specifically, sensors are first deployed at multiple pre-selected nodes in the grounding grid. These nodes are measurement locations pre-selected based on the grounding grid structure and diagnostic requirements. These include grounding grid edges for analyzing current spread and boundary effects, branch nodes (T-shaped or cross-shaped) for analyzing current distribution and connection point status, and pre-selected areas for targeted monitoring and diagnosis (such as historical corrosion zones or areas below critical equipment). Then, high-frequency voltage and current sensors are simultaneously deployed at each node. The high-frequency voltage sensor typically uses a capacitive voltage divider principle, featuring wide bandwidth and high input impedance, to measure the high-frequency voltage signal at a point on the grounding grid relative to ground. The high-frequency current sensor typically uses a Rogowski coil principle—a coreless air coil—which has extremely high response speed to high-frequency current changes, used to measure the high-frequency current signal flowing into or out of a branch of the grounding grid. Finally, after excitation is initiated, the high-frequency voltage and current sensors at each node synchronously acquire continuous time-domain voltage and current signals within each complete waveform cycle, completely preserving all time-domain waveform data, including edge segments, flat-top segments, positive half-cycles, and negative half-cycles, without any missing segments.

[0077] This step involves synchronous acquisition of features from multiple spatial points, across the entire cycle, and across the entire waveform. This provides complete and reliable data support for subsequent edge / flat-top frequency domain component splitting, dual impedance spectrum calculation, and distributed fault tracing and diagnosis, completely avoiding the defects of waveform feature loss and inability to segment analysis caused by traditional single-point acquisition and segment acquisition.

[0078] This step involves synchronous acquisition of features from multiple spatial points, across the entire cycle, and across the entire waveform. This provides complete and reliable data support for subsequent edge / flat-top frequency domain component splitting, dual impedance spectrum calculation, and distributed fault tracing and diagnosis, completely avoiding the defects of waveform feature loss and inability to segment analysis caused by traditional single-point acquisition and segment acquisition.

[0079] In another aspect of this step, when acquiring the grounding grid response signal, an adaptive filtering algorithm and waveform feature point verification technology are further employed. Specifically, by analyzing the real-time spectral characteristics of environmental noise, the cutoff frequency of the Butterworth low-pass filter is dynamically adjusted to suppress noise interference in non-target frequency bands. Simultaneously, redundancy verification is performed using the regular waveform characteristics of odd-symmetric bipolar trapezoidal waves (such as edges and flat-top segments) to eliminate abnormal waveform data caused by noise interference: by comparing waveform feature points (such as rise time and flat-top segment amplitude) measured multiple times, abnormal data caused by noise is eliminated. Furthermore, the impedance spectra measured multiple times are superimposed and averaged to eliminate the influence of random noise and enhance the signal-to-noise ratio in key frequency bands.

[0080] S104. Perform frequency domain conversion on the voltage and current signals to determine the high-frequency impedance characteristics.

[0081] In this step, after completing the wideband excitation injection and full waveform time-domain signal synchronous acquisition through the aforementioned steps, the time-domain voltage and current signals are deeply processed through a dedicated frequency-domain analysis mechanism, and finally decoupled to obtain the high-precision high-frequency impedance characteristics of the grounding grid.

[0082] Based on the extensive approach of single-frequency point-by-point testing of sinusoidal waves and indiscriminate overall spectrum analysis of even-symmetric triangular waves used in existing technologies, this application leverages the inherent time-domain segmentation advantage of odd-symmetric bipolar trapezoidal waves. Instead of performing general spectrum calculations on the entire waveform, it specifically separates the frequency domain components corresponding to high-frequency edge characteristics and mid-to-low-frequency flat-top characteristics, thereby achieving decoupled detection of conductor high-frequency characteristics and soil steady-state characteristics. This fundamentally solves the technical problems of mixed frequency band characteristics, inability to trace defects, and loss of high-frequency details in existing technologies.

[0083] This application employs odd-symmetric bipolar trapezoidal waves to achieve full coverage of the high-frequency transient band from the power frequency to tens of MHz with a single excitation, completely eliminating the problems of low efficiency and insufficient high-frequency excitation energy in traditional point-by-point frequency scanning, and significantly improving on-site detection efficiency and adaptability to high-frequency operating conditions. Secondly, relying on the natural segmentation characteristics of the waveform, it achieves physical decoupling between the high-frequency response of the grounding grid conductor and the steady-state response of the soil, overcoming the drawbacks of mixed spectral characteristics and inability to distinguish defect causes in existing technologies, providing a new technical dimension for fault tracing and diagnosis. Finally, combining multi-node distributed acquisition and adaptive noise reduction optimization, it fully preserves the characteristics of weak high-frequency defects, effectively improving the measurement signal-to-noise ratio and data fidelity in complex electromagnetic environments, laying a solid and reliable technical foundation for subsequent high-precision impedance spectrum solving, high-frequency characteristic analysis, and refined defect localization.

[0084] Figure 2 This is a flowchart illustrating Embodiment Two of the method for analyzing the high-frequency impedance characteristics of the grounding grid provided in this application. Figure 2 As shown, in Figure 1 Based on the previous embodiment, frequency domain transformation is performed on the voltage and current signals to decompose them into edge frequency domain components and flat-top frequency domain components, and the high-frequency impedance characteristics are accurately determined. Specifically, this includes:

[0085] S201. Perform frequency domain conversion on the voltage and current signals to obtain edge frequency domain components and flat-top frequency domain components.

[0086] This step overcomes the inherent limitations of traditional sinusoidal wave excitation (lack of segmentation) and even-symmetric triangular waves (inability to separate high and low frequency features). Specifically, it includes three steps: signal preprocessing, overall frequency domain transformation, and differential component extraction.

[0087] First, the acquired raw voltage and current signals are preprocessed to obtain the target voltage and current signals. Specifically, a combined noise reduction method using wavelet transform and Butterworth filtering is employed, along with a standard load system error calibration mechanism. This effectively filters out complex electromagnetic interference, random noise, and system stray errors from the field, while fully preserving the high-frequency abrupt changes at the steep edges of the odd-symmetric bipolar trapezoidal wave and the steady-state characteristics of the flat-top segment. This overcomes the problems of traditional single filtering, which tends to smooth out high-frequency details and result in low high-frequency signal-to-noise ratios, providing a high-fidelity original waveform for subsequent high-precision frequency domain analysis.

[0088] Secondly, the preprocessed target voltage and current signals undergo frequency domain transformation to obtain full-domain frequency domain signals. Specifically, a windowed Fast Fourier Transform is used to completely map the normalized time-domain waveform to the frequency domain dimension, obtaining complex frequency domain data containing amplitude and phase information across the entire frequency band. Relying on the rich odd harmonic characteristics of trapezoidal waves, it can cover high-frequency transient bands from power frequency to tens of MHz in one go, without the need for point-by-point iterative scanning as in the sine wave frequency sweep method, significantly improving testing efficiency and frequency band coverage integrity.

[0089] Finally, based on the inherent time-domain segmentation intervals of the trapezoidal wave, the full-domain frequency domain signal is precisely decomposed, and the edge frequency domain components corresponding to the steep rising and falling edges of the waveform, as well as the flat-top frequency domain components corresponding to the smooth and continuous flat-top segments of the waveform, are extracted. Among them, the edge frequency domain components are rich in ultra-high frequency harmonic energy, accurately corresponding to the high-frequency electromagnetic response of the grounding grid conductor and connection nodes; the flat-top frequency domain components are concentrated in the mid-to-low frequency band, accurately corresponding to soil leakage and quasi-steady-state current dissipation response, realizing the physical decoupling of the grounding grid conductor's intrinsic characteristics and the soil environment characteristics, and completely solving the industry pain point of existing technologies where the two types of characteristics are mixed and the cause of defects cannot be distinguished.

[0090] S202. Calculate the edge impedance spectrum and the flat-top impedance spectrum based on the edge frequency domain components and the flat-top frequency domain components.

[0091] This step constructs a two-dimensional dedicated impedance spectrum based on the two independent frequency domain components after decoupling. Specifically, the edge impedance spectrum is obtained by solving the frequency domain complex impedance calculation based on the edge frequency domain components. This impedance spectrum is specifically used to characterize the propagation differences and skin effect changes of grounding grid conductors and connection nodes under high-frequency operating conditions, and has ultra-high sensitivity to minor defects in the conductor itself, such as conductor corrosion, cross-sectional attenuation, joint loosening, and local fracture.

[0092] The flat-top impedance spectrum is obtained by synchronously solving the flat-top frequency domain components. This impedance spectrum is specifically used to characterize the leakage capacity and quasi-steady-state conduction state of the soil around the grounding grid. It can accurately reflect the fluctuations of environmental parameters such as uneven soil resistivity stratification, humidity variation, and soil aging.

[0093] In one possible implementation, when the edge impedance spectrum and the flat-top impedance spectrum show different trends in the same measurement area, it can help determine whether the anomaly is more inclined to the conductor itself or the soil environment.

[0094] For example, suppose the first The measurement point at the th harmonic frequencies The frequency domain quantities of voltage and current corresponding to the edge segment and the flat-top segment are respectively , , , Then the piecewise impedance can be expressed as:

[0095]

[0096] in, Edge impedance spectrum;

[0097] It is a flat-topped impedance spectrum;

[0098] This is a piecewise difference measure used to characterize the difference between the high-frequency propagation response of the conductor and the quasi-steady-state conductivity response of the soil.

[0099] Let the first The measurement point at the th harmonic frequencies At the location, the frequency domain voltages extracted for the corresponding time periods of the positive and negative half-cycles are respectively , The frequency domain currents are respectively , To reduce the impact of sign direction and low-frequency drift, corresponding verification can be performed on the positive and negative half-cycle responses. The synchronization verification impedance can then be expressed as:

[0100]

[0101] in, This is the synchronous impedance after corresponding verification of the positive and negative half-cycles, used to reduce the influence of DC bias, ground potential drift and common-mode error of the measurement channel on the impedance spectrum.

[0102] For odd-symmetric bipolar trapezoidal waves, under ideal linear conditions, the voltage and current response amplitudes of the positive and negative half-cycles are equal but their polarities are opposite. Based on this correspondence, when performing differential or consistency checks on the positive and negative half-cycle responses, common-mode errors, DC bias, and low-frequency drift components can be offset or reduced while maintaining the consistency of the measured impedance calculation.

[0103] The amplitude and phase of the synchronous impedance spectrum are compared with those of the theoretical impedance spectrum. Let the theoretical impedance be... Then the comprehensive defect characteristic quantity can be expressed as:

[0104]

[0105] in, , used to indicate amplitude deviation;

[0106] , used to represent phase deviation;

[0107] a, b, and c are weighting coefficients.

[0108] In the specific implementation process, when adjacent measurement points A sustained increase at multiple harmonic frequencies indicates a high probability of conductor corrosion, breakage, or poor connection in the corresponding region. The aforementioned weighting coefficients and preset thresholds can be calibrated using measured samples or finite element simulation samples from normal and known defective regions; alternatively, equal weights can be used as initial values, and then the weights can be adjusted based on known field samples. The threshold can be determined based on the statistical distribution of comprehensive defect characteristics in the normal region.

[0109] Existing technologies, whether sinusoidal frequency sweeping or conventional triangular wave detection, can only output the overall equivalent impedance of the grounding grid, failing to distinguish whether impedance anomalies originate from conductor damage or soil environmental changes, resulting in vague and delayed fault diagnosis. This step, through independent calculation of dual impedance spectra, fundamentally expands the detection dimensions, providing core data support for defect source tracing and classification.

[0110] S203. Extract the amplitude-frequency and phase-frequency characteristics of the edge impedance spectrum and the flat-top impedance spectrum to determine the high-frequency impedance characteristics.

[0111] In this step, the amplitude-frequency response curves and phase-frequency response curves of the edge impedance spectrum and the flat-top impedance spectrum are extracted independently, while the amplitude variation law and phase shift law are preserved simultaneously, avoiding the detection defect of traditional technology that only focuses on the impedance magnitude and discards phase-sensitive information.

[0112] Based on this, the amplitude and phase frequency multi-dimensional characteristics of the dual impedance spectrum are fused and processed, and the high-frequency variation characteristics of the conductor and the steady-state offset characteristics of the soil are integrated to obtain a complete impedance spectrum of the grounding grid that covers the entire effective frequency band and has both spatial and frequency dimension information. Finally, the global high-frequency impedance characteristics of the grounding grid are determined comprehensively and accurately.

[0113] This step fully utilizes the high sensitivity of phase parameters to minute structural defects and combines them with the differentiated response characteristics of dual impedance spectra. It can accurately capture subtle parameter changes caused by the high-frequency skin effect, enabling early warning of hidden defects in the grounding grid. Furthermore, it can restore the true high-frequency operating condition response of the grounding grid through feature fusion. This solves the technical problems of missing high-frequency features, low detection accuracy, and one-sided condition assessment in traditional technologies, greatly improving the comprehensiveness and accuracy of high-frequency condition assessment of the grounding grid.

[0114] This application's embodiment, through a complete and innovative link of preprocessing fidelity, frequency domain segmentation decoupling, independent calculation of dual impedance spectra, and amplitude-phase feature fusion, is completely different from the existing technical solutions of sine wave point-by-point frequency sweeping and conventional triangular wave overall spectrum analysis. It achieves technical breakthroughs in broadband high-efficiency detection, feature decoupling and source tracing, and precise amplitude-phase dual-dimensional evaluation, providing reliable technical support for subsequent refined fault location and status assessment of grounding grids.

[0115] Figure 3This is a flowchart illustrating Embodiment 3 of the method for analyzing the high-frequency impedance characteristics of the grounding grid provided in this application. Figure 3 As shown, in this embodiment... Figure 1 Based on the previous embodiment, after calculating the impedance spectrum of the grounding grid according to the edge frequency domain components and the flat-top frequency domain components, and determining the high-frequency impedance characteristics, the method further includes:

[0116] S301. Collect the physical and geometric parameters of the grounding grid and the electrical parameters of the soil.

[0117] Among them, physical geometric parameters refer to the characteristic quantities that describe the physical shape and spatial position of the grounding grid, including the grounding grid size and conductor burial depth, grid spacing, conductor cross-sectional diameter and other structural characteristic parameters. The grounding grid size usually refers to the length and width of the grounding grid on the horizontal plane, as well as the spacing of the conductor grid. The conductor burial depth refers to the vertical distance from the top of the horizontal conductor of the grounding grid to the ground surface.

[0118] Soil electrical parameters are physical quantities used to describe the electrical and dielectric properties of soil. Their values ​​vary with frequency and include frequency-dependent environmental electrical parameters such as soil conductivity and complex permittivity. Soil conductivity measures the soil's ability to conduct electricity; at low frequencies, it dominates the current dissipation characteristics of the grounding grid. The complex permittivity is a complex number describing the polarization and loss characteristics of soil in an alternating electric field; at high frequencies, the dielectric properties of soil become significant, and its frequency dependence cannot be ignored.

[0119] This step aims to obtain the raw environmental and structural data required to establish a high-precision theoretical model. For example, first, consult the as-built drawings or design documents of the grounding grid to obtain the total dimensions, grid spacing, conductor diameter (or equivalent radius), and burial depth of the grounding grid. For older grounding grids, verification can be performed through local excavation or ground-penetrating radar detection. Then, in the area where the grounding grid is located, use a four-electrode Wenner device to measure the apparent resistivity of the soil at different depths and locations, and obtain the layered soil model and its low-frequency conductivity through inversion calculation. Considering high-frequency characteristics, it is necessary to obtain or estimate the complex dielectric constant spectrum of the soil. This can be done by collecting soil samples for laboratory frequency domain dielectric spectrum measurement, or by using known dielectric models of typical soil types (such as sandy soil and clay) combined with measured low-frequency conductivity for estimation.

[0120] This step, by collecting real geometric parameters and considering the frequency-dependent complex permittivity of the soil, provides accurate input for constructing a high-frequency distributed parameter model that more closely resembles the actual physical world. This ensures that the theoretical model can more accurately simulate the real electromagnetic behavior of the grounding grid at high frequencies, especially the displacement current effect and loss characteristics of the soil at high frequencies, laying a scientific benchmark for subsequent accurate comparison with measured data.

[0121] S302. Based on the physical geometric parameters and soil electrical parameters, construct a theoretical model of the distributed parameters of the grounding grid.

[0122] The distributed parameter theory model is a theoretical model that treats the conductor of a grounding grid as a transmission line or network with resistance, inductance, capacitance, and conductance distributed along its length. Unlike lumped parameter models (such as a single RLC), it acknowledges that electromagnetic waves take time to propagate along the conductor, the parameters are values ​​per unit length, and the resistance, inductance, capacitance, and conductance can all vary with frequency.

[0123] This step transforms the raw parameters collected by S301 into a mathematical model that can be used for calculation. For example, firstly, based on the geometric dimensions (radius, burial depth) of the grounding grid conductors and the electrical parameters of the soil, electromagnetic field theory formulas are applied to calculate resistance, inductance, capacitance, and conductance. Then, a two-dimensional network model is constructed, discretizing the entire horizontal grounding grid into a two-dimensional mesh composed of multiple "T-shaped" or "π-shaped" units. Each unit represents a small segment of conductor, and its characteristics are obtained by multiplying the calculated unit-length parameters (resistance, inductance, capacitance, and conductance) by the unit length. This model fully preserves the two-dimensional topology of the grounding grid.

[0124] Furthermore, a deep learning algorithm is introduced for self-calibration when constructing the theoretical model of the distributed parameters of the grounding grid. Specifically, a deep neural network is trained using historical measured impedance spectrum data (including samples with different soil conditions and conductor states) to learn the nonlinear mapping relationship between distributed parameters (such as the soil complex permittivity and the conductor skin effect coefficient) and the impedance spectrum. In real-time analysis, the measured impedance spectrum and grounding grid physical parameters (such as conductor size and burial depth) are input, and the key coefficients in the distributed parameter model are dynamically corrected through the trained model. For example, in the high-frequency band, traditional models may lead to impedance calculation errors due to neglecting the soil capacitance effect, while the self-calibration model can dynamically compensate for this error by correcting the soil complex permittivity in real time, thereby improving the accuracy of high-frequency impedance calculation.

[0125] This step constructs a two-dimensional distributed parameter model with clearly defined physical meaning and parameters varying with frequency. This model can simulate the skin effect, electromagnetic coupling between conductors, and high-frequency dielectric behavior of soil from a mechanistic perspective, thereby theoretically predicting the complex impedance response of the grounding grid over a wide frequency band (especially the high-frequency band). This is a prerequisite for achieving high-precision diagnostic comparison and is also the core embodiment of the scientific rigor and advancement of the method in this invention.

[0126] S303. Based on the theoretical model of the distributed parameters of the grounding grid, the theoretical impedance spectrum of the grounding grid is calculated.

[0127] The theoretical impedance spectrum refers to the function of input impedance or transfer impedance as a function of frequency between a specified excitation point (consistent with the measured injection point) and a measurement point (consistent with the measured sensor position), obtained through circuit simulation or analytical calculation based on the aforementioned distributed parameter theoretical model.

[0128] Specifically, this step involves generating an "ideal health state" reference standard for comparison using a theoretical model. First, in a circuit simulation environment, the two-dimensional distributed parameter network constructed by S302 is accurately reproduced, with the excitation source (voltage source or current source) set at the same injection node as in the actual measurement. Circuit simulation refers to using circuit simulation software to build the two-dimensional distributed parameter network model constructed by S302, setting port conditions consistent with the actual measurement, and performing frequency domain scanning analysis.

[0129] Then, measurement ports are set up at each sensor node, identical to those in the actual measurements. Frequency domain analysis (AC analysis) is performed on the model, scanning a frequency range covering the effective harmonic frequency band of the bipolar trapezoidal wave excitation (e.g., from the fundamental frequency to the highest effective harmonic). Finally, the simulation software directly outputs the complex impedance values ​​of each measurement port at discrete frequency points. Similarly, its amplitude and phase can be extracted to generate theoretical amplitude-frequency / phase-frequency curves and theoretical two-dimensional impedance distribution diagrams.

[0130] This step provides a first-principles-based, quantitative health benchmark, changing the traditional approach that relies primarily on historical data or procedural thresholds for fuzzy judgments. The final calculated theoretical impedance spectrum represents the impedance characteristics that an "ideal, defect-free" grounding grid should possess under the current soil environment and grounding grid design dimensions. It provides an objective and precise reference scale for subsequent comparative diagnosis, allowing any deviations to be quantified and analyzed, greatly improving the scientific rigor and accuracy of the condition assessment.

[0131] S304. Compare the theoretical impedance spectrum with the calculated impedance spectrum of the grounding grid to obtain the operating status of the grounding grid.

[0132] The operational status is a comprehensive evaluation of the health condition of the grounding grid, which may include qualitative judgments such as "healthy", "slight corrosion", "local fracture", "poor connection" and "uneven soil", as well as quantitative information such as the location and severity of defects.

[0133] This step is the final diagnostic and assessment stage, revealing potential defects through comparison. For example, for each measurement node and each harmonic frequency point, the relative deviation between the measured and theoretical impedance is calculated. If the deviation of all nodes at all frequencies is within a very small threshold (e.g., ±5%), the grounding grid is considered to be in healthy operation. If the deviation is mainly manifested in the high-frequency range (e.g., >1MHz), and the amplitude-frequency deviation is positive and increases with frequency, it strongly indicates an intensified skin effect, possibly caused by a reduction in conductor cross-section (corrosion). If the deviation only appears at one or a few specific spatial nodes, while other locations are normal, it is considered a local defect. By drawing a two-dimensional distribution map of the amplitude-frequency deviation or phase-frequency deviation, the defect area (e.g., a grid edge or connection point) can be visually located.

[0134] Finally, the deviation mode is used for judgment. For conductor corrosion, it usually leads to a significant increase in high-frequency resistance, which is manifested as an increase in the high-frequency band, and the phase may also change characteristically. For the case of complete conductor breakage, it leads to the interruption of the signal path, which is manifested as a sharp increase in the impedance amplitude of the node after the break point and a drastic change in phase. For the case of connection point deterioration (poor soldering, loosening), by introducing additional contact resistance and nonlinearity, it may cause abnormal fluctuations in impedance and phase in multiple frequency bands.

[0135] This step achieves a closed loop from "measurement" to "diagnosis," solving the problems of traditional methods such as limited assessment dimensions, vague diagnostic criteria, and insensitivity to early and localized defects. By systematically comparing high-fidelity measured data with high-precision physical models, it enables refined and intelligent diagnosis of the grounding grid's operating status. This significantly improves the foresight, targeting, and economy of grounding grid condition-based maintenance, preventing problems before they occur and avoiding serious accidents caused by the development of latent grounding grid faults. It perfectly achieves all the technical objectives of this invention and produces significant technical effects that surpass existing technologies.

[0136] The method for analyzing the high-frequency impedance characteristics of grounding grids provided in Embodiment 3 of this application, based on the high-precision measured impedance spectrum obtained in Embodiments 1 and 2, introduces a distributed parameter theoretical model constructed based on real physical geometric parameters and frequency-dependent soil electrical parameters, and performs a systematic measured-theoretical comparison. This deeply integrates advanced measurement technology based on bipolar trapezoidal wave excitation with precise modeling technology based on first principles, achieving a fundamental improvement in the assessment of grounding grid operation status from "qualitative perception" to "quantitative diagnosis," and from "overall evaluation" to "precise local measurement." It can sensitively and accurately identify and locate early or local defects caused by corrosion, fracture, etc., providing an unprecedentedly powerful technical tool for the precise operation and maintenance and risk prevention of power system grounding grids, completely overcoming the limitations of model distortion and coarse diagnosis in existing technologies.

[0137] Figure 4A schematic diagram of the bipolar trapezoidal wave excitation provided in this application. Figure 4 As shown, this invention provides a method and application for analyzing the high-frequency impedance characteristics of a grounding grid based on bipolar trapezoidal wave excitation. By employing a bipolar trapezoidal wave excitation signal and fully utilizing the rich harmonic components of the bipolar trapezoidal wave, the high-frequency impedance characteristics of the grounding grid over a wide frequency range can be effectively obtained. This overcomes the shortcomings of traditional sinusoidal wave excitation methods, improves the accuracy and comprehensiveness of the high-frequency characteristic analysis of the grounding grid, and provides strong support for the safe and stable operation of the power system.

[0138] Specifically, a bipolar trapezoidal wave is a periodic non-sinusoidal component that can be expanded into a Fourier series, i.e., decomposed into a series of superimposed sinusoidal quantities with different frequencies, containing a fundamental wave and a series of odd harmonics (such as the 3rd, 5th, 7th, etc.). For example, with a period of T and an amplitude of... Bipolar trapezoidal waves, such as Figure 4 As shown, the corresponding expression is as follows:

[0139]

[0140] in, For the rising time, For the time of the flat top, .

[0141] For a bipolar trapezoidal wave signal, the wavelengths corresponding to each frequency component still satisfy... The fundamental frequency is the speed at which the signal propagates in the transmission medium (where f is the frequency). Corresponding wavelength nth harmonic frequency (n=1,3,5,...,2n-1), corresponding wavelength .

[0142] For an odd-symmetric bipolar trapezoidal wave, after Fourier series decomposition, it can be expressed as:

[0143]

[0144] in, For bipolar trapezoidal wave amplitude, The fundamental frequency of the bipolar trapezoidal wave ( , (for periodicity) The proportion of the rise time of the trapezoidal wave to half a cycle. .

[0145] For an odd-symmetric bipolar trapezoidal wave, after decomposition, it can be represented as a superposition of sine functions, exhibiting clear odd harmonic characteristics and having no DC component. Compared to even-symmetric waveforms, odd-symmetric trapezoidal waves avoid the influence of DC bias, simplify harmonic impedance matching calculations, are more conducive to the transmission efficiency of high-frequency signals, and are more consistent with practical systems. This invention uses odd-symmetric bipolar trapezoidal waves.

[0146] On the other hand, the analysis of the grounding grid impedance spectrum in this application only considers the horizontal grounding grid and ignores the vertical grounding body and natural grounding body; the mutual inductance and mutual resistance parameters between conductors are averaged to a single conductor; the distribution parameters in the transverse (x direction) and longitudinal (y direction) directions are the same, and weak coupling between conductors is ignored.

[0147] The two-dimensional input impedance of the grounding grid along the x and y directions is as follows:

[0148]

[0149] in, Let Z0 be the load reflection coefficient, Z0 be the wave impedance, and γ be the propagation constant. Both Z0 and γ depend on the characteristics of the grounding grid itself. The frequency response characteristics of the grounding grid's input impedance are measured, combined with the propagation constant... The position dependence can resolve the exponential decay term in the impedance spectrum. , and reflection coefficient The changes in impedance result in differences in the amplitude and phase frequency characteristics of the grounding grid impedance spectrum. When a local conductor breaks, corrodes, or has poor contact, a sudden change in load impedance leads to… Anomalies are identified by comparing the frequency domain deviation between measured and theoretical impedance spectra to evaluate the performance of the grounding grid.

[0150] Substituting the function of the bipolar trapezoidal wave excitation into the grounding grid impedance spectrum calculation, we obtain the frequency of each harmonic. The input impedance is:

[0151]

[0152] in, Given the load impedance, characteristic impedance, and propagation coefficient, they can be expressed as:

[0153]

[0154] Then, the impedance spectra at each harmonic frequency are summed to obtain the total impedance spectrum of the grounding grid:

[0155]

[0156] in, Indicates frequency at Discrete components at that point, Given the zero-frequency input impedance, the high-frequency performance of the grounding grid can be evaluated based on the grounding grid impedance spectrum obtained from the above formula.

[0157] Figure 5 The experimental results are shown in the figure, illustrating the analytical method for the high-frequency impedance characteristics of the grounding grid provided in this application. Figure 5 Figure a shows a diagram of a bipolar trapezoidal wave signal output by a bipolar trapezoidal wave signal generator, which includes an ideal trapezoidal wave, a noisy signal, and a filtered signal.

[0158] like Figure 5 Figure b shows a comparison of impedance amplitude characteristics under different excitations. This includes impedance amplitude characteristics under sinusoidal wave excitation, triangular wave excitation, and trapezoidal wave excitation.

[0159] like Figure 5 Figure c shows a comparison of impedance-phase characteristics under different excitation methods. This includes impedance-phase characteristics under sinusoidal wave excitation, triangular wave excitation, and trapezoidal wave excitation.

[0160] Figure 6 A schematic diagram of the structure of the grounding grid high-frequency impedance characteristic analysis device 60 provided in this application. Figure 6 As shown, the grounding grid high-frequency impedance characteristic analysis device 60 provided in this embodiment includes:

[0161] The excitation signal generation module 601 is used to generate an odd-symmetric bipolar trapezoidal wave excitation signal. The fundamental frequency of the odd-symmetric bipolar trapezoidal wave excitation signal is in the range of 1kHz to 10MHz, and its rise time is less than 200ns.

[0162] The signal injection module 602 is used to amplify the odd-symmetric bipolar trapezoidal wave excitation signal and then inject it into the grounding grid.

[0163] The signal acquisition module 603 is used to acquire the voltage and current signals of the grounding grid in response to the odd-symmetric bipolar trapezoidal wave excitation signal;

[0164] Frequency domain conversion module 604 is used to perform frequency domain conversion processing on voltage signals and current signals to obtain edge frequency domain components and flat-top frequency domain components;

[0165] The impedance characteristic determination module 605 is used to calculate the impedance spectrum of the grounding grid based on the edge frequency domain component and the flat top frequency domain component, and to determine the high-frequency impedance characteristics.

[0166] Furthermore, the excitation signal generation module 601 is also specifically used for:

[0167] Determine the bipolar trapezoidal wave signal generator;

[0168] Adjust the duty cycle of the bipolar trapezoidal wave signal generator to obtain the target fundamental frequency;

[0169] The target rise time is obtained by adjusting the rise time of the bipolar trapezoidal wave signal generator;

[0170] Based on the target fundamental frequency and the target rise time, an odd-symmetric bipolar trapezoidal wave excitation signal is generated.

[0171] Furthermore, the frequency domain conversion module 604 is also specifically used for:

[0172] The voltage and current signals are preprocessed to obtain the target voltage and target current signals;

[0173] The target voltage signal and the target current signal are subjected to frequency domain transformation to obtain the frequency domain signal;

[0174] Based on the time-domain segmentation intervals of the trapezoidal wave, the edge frequency domain components corresponding to the rising and falling edges of the waveform and the flat-top frequency domain components corresponding to the smooth flat-top segments of the waveform are extracted from the frequency domain signal.

[0175] Furthermore, the signal injection module 602 is also specifically used for:

[0176] Based on the power amplifier, the odd-symmetric bipolar trapezoidal wave excitation signal is amplified to obtain the amplified excitation signal;

[0177] The amplified excitation signal is coupled using a frequency conversion isolation transformer and then injected into the grounding grid.

[0178] Furthermore, the signal acquisition module 603 is also specifically used for:

[0179] High-frequency voltage sensors and high-frequency current sensors are respectively arranged at multiple preset nodes of the grounding grid;

[0180] The system synchronously acquires continuous voltage and current signals within each complete waveform cycle, including all time-domain waveforms of the edge segment, flat-top segment, positive half-cycle, and negative half-cycle within each complete waveform cycle.

[0181] The preset nodes include at least one of the following: the edge of the grounding grid, the branch node, and the preset corrosion risk area.

[0182] Furthermore, the impedance characteristic determination module 605 is also specifically used for:

[0183] Based on the edge frequency domain components and the flat-top frequency domain components, the edge impedance spectrum and the flat-top impedance spectrum are calculated. The edge impedance spectrum is used to characterize the high-frequency propagation difference between the conductor and the connection node, and the flat-top impedance spectrum is used to characterize soil leakage and quasi-steady-state conduction state.

[0184] Extract the amplitude-frequency and phase-frequency characteristics of the edge impedance spectrum and the flat-top impedance spectrum;

[0185] The amplitude-frequency and phase-frequency characteristics are fused to obtain the complete impedance spectrum of the grounding grid and determine the high-frequency impedance characteristics.

[0186] Furthermore, the impedance characteristic determination module 605 is also specifically used for:

[0187] Collect the physical and geometric parameters of the grounding grid and the electrical parameters of the soil;

[0188] Based on physical geometric parameters and soil electrical parameters, a theoretical model of the distributed parameters of the grounding grid is constructed.

[0189] Based on the theoretical model of the distributed parameters of the grounding grid, the theoretical impedance spectrum of the grounding grid is calculated.

[0190] The operating status of the grounding grid is obtained by comparing the theoretical impedance spectrum with the calculated impedance spectrum of the grounding grid.

[0191] The grounding grid high-frequency impedance characteristic analysis device provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0192] Figure 7 A schematic diagram of the structure of the analysis equipment for the high-frequency impedance characteristics of the grounding grid provided in this application. Figure 7 As shown, the grounding grid high-frequency impedance characteristic analysis device 70 provided in this embodiment includes at least one processor 701 and a memory 702. Optionally, the device 70 further includes a communication component 703. The processor 701, memory 702, and communication component 703 are connected via a bus 704.

[0193] In a specific implementation, at least one processor 701 executes computer execution instructions stored in memory 702, causing at least one processor 701 to perform the above-described method.

[0194] The specific implementation process of processor 701 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0195] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0196] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0197] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0198] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0199] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0200] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0201] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0202] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0203] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0204] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0205] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0206] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0207] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for analyzing the high-frequency impedance characteristics of a grounding grid, characterized in that, include: An odd-symmetric bipolar trapezoidal wave excitation signal is generated, wherein the fundamental frequency of the odd-symmetric bipolar trapezoidal wave excitation signal is in the range of 1 kHz to 10 MHz, and its rise time is less than 200 ns. The odd-symmetric bipolar trapezoidal wave excitation signal is amplified and then injected into the grounding grid. The voltage and current signals of the grounding grid in response to the odd-symmetric bipolar trapezoidal wave excitation signal are collected. The voltage signal and the current signal are subjected to frequency domain conversion to obtain edge frequency domain components and flat-top frequency domain components; The impedance spectrum of the grounding grid is calculated based on the edge frequency domain component and the flat-top frequency domain component to determine the high-frequency impedance characteristics.

2. The analytical method according to claim 1, characterized in that, Generating an odd-symmetric bipolar trapezoidal wave excitation signal includes: Determine the bipolar trapezoidal wave signal generator; Adjust the duty cycle of the bipolar trapezoidal wave signal generator to obtain the target fundamental frequency; The target rise time is obtained by adjusting the rise time of the bipolar trapezoidal wave signal generator. Based on the target fundamental frequency and the target rise time, an odd-symmetric bipolar trapezoidal wave excitation signal is generated.

3. The analytical method according to claim 1, characterized in that, The voltage signal and the current signal are subjected to frequency domain transformation to obtain edge frequency domain components and flat-top frequency domain components, including: The voltage signal and the current signal are preprocessed to obtain the target voltage signal and the target current signal; The target voltage signal and the target current signal are subjected to frequency domain conversion to obtain a frequency domain signal; Based on the time-domain segmentation interval of the trapezoidal wave, the edge frequency domain components corresponding to the rising and falling edges of the waveform and the flat-top frequency domain components corresponding to the flat-top segments of the waveform are extracted from the frequency domain signal.

4. The analytical method according to any one of claims 1 to 3, characterized in that, After amplifying the odd-symmetric bipolar trapezoidal wave excitation signal, it is injected into the grounding grid, including: The odd-symmetric bipolar trapezoidal wave excitation signal is amplified using a power amplifier to obtain an amplified excitation signal. The amplified excitation signal is coupled using a frequency conversion isolation transformer and then injected into the grounding grid.

5. The analytical method according to any one of claims 1 to 3, characterized in that, The process of acquiring the voltage and current signals of the grounding grid in response to the odd-symmetric bipolar trapezoidal wave excitation signal includes: High-frequency voltage sensors and high-frequency current sensors are respectively arranged on multiple preset nodes of the grounding grid; The voltage and current signals are acquired synchronously within each complete waveform cycle, wherein each complete waveform cycle includes all time-domain waveforms of the edge segment, the flat-top segment, the positive half-cycle, and the negative half-cycle. The preset node includes at least one of the following: grounding grid edge, branch node, and preset corrosion risk area.

6. The analytical method according to any one of claims 1 to 3, characterized in that, Based on the edge frequency domain component and the flat-top frequency domain component, the impedance spectrum of the grounding grid is calculated to determine the high-frequency impedance characteristics, including: The edge impedance spectrum and the flat-top impedance spectrum are calculated based on the edge frequency domain component and the flat-top frequency domain component. The edge impedance spectrum is used to characterize the high-frequency propagation difference between the conductor and the connection node, and the flat-top impedance spectrum is used to characterize soil leakage and quasi-steady-state conduction state. Extract the amplitude-frequency and phase-frequency characteristics of the edge impedance spectrum and the flat-top impedance spectrum; The amplitude-frequency characteristic and the phase-frequency characteristic are fused to obtain the complete impedance spectrum of the grounding grid, and the high-frequency impedance characteristics are determined.

7. The analytical method according to any one of claims 1 to 3, characterized in that, Based on the edge frequency domain component and the flat-top frequency domain component, the impedance spectrum of the grounding grid is calculated, and the high-frequency impedance characteristics are determined. The method further includes: Collect the physical geometric parameters of the grounding grid and the electrical parameters of the soil; Based on the physical geometric parameters and the soil electrical parameters, a theoretical model of the distributed parameters of the grounding grid is constructed; Based on the theoretical model of the distributed parameters of the grounding grid, the theoretical impedance spectrum of the grounding grid is calculated. The operating status of the grounding grid is obtained by comparing the theoretical impedance spectrum with the calculated impedance spectrum of the grounding grid.

8. A device for analyzing the high-frequency impedance characteristics of a grounding grid, characterized in that, include: An excitation signal generation module is used to generate an odd-symmetric bipolar trapezoidal wave excitation signal, wherein the fundamental frequency of the odd-symmetric bipolar trapezoidal wave excitation signal is in the range of 1 kHz to 10 MHz and its rise time is less than 200 ns. The signal injection module is used to amplify the odd-symmetric bipolar trapezoidal wave excitation signal and then inject it into the grounding grid. The signal acquisition module is used to acquire the voltage and current signals of the grounding grid in response to the odd-symmetric bipolar trapezoidal wave excitation signal; The frequency domain conversion module is used to perform frequency domain conversion processing on the voltage signal and the current signal to obtain edge frequency domain components and flat-top frequency domain components. The impedance characteristic determination module is used to calculate the impedance spectrum of the grounding grid based on the edge frequency domain component and the flat-top frequency domain component, and to determine the high-frequency impedance characteristics.

9. An analysis device for the high-frequency impedance characteristics of a grounding grid, characterized in that, include: Memory, processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the method as described in any one of claims 1-7.

10. A computer program product, characterized in that, Includes a computer program that, when executed by a processor, implements the method described in any one of claims 1-7.

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