Grounding grid high-frequency impedance analysis method and device and electronic equipment

Abstract

The invention provides a grounding grid high-frequency impedance analysis method and device and electronic equipment, and relates to the technical field of power systems and electric measurement. The method comprises the steps that a triangular wave excitation signal is acquired, and the triangular wave excitation signal is an even symmetric triangular wave signal constructed based on preset fundamental wave frequency and amplitude and is used for being injected into a grounding grid; based on the triangular wave excitation signal, response signals of the grounding grid at a plurality of measurement points are obtained, and the response signals comprise a high-frequency voltage signal and a high-frequency current signal; and based on the response signal and the distribution parameter model, determining an input impedance spectrum of the grounding grid, the input impedance spectrum being used for evaluating a high-frequency impedance characteristic of the grounding grid. The method is used for improving the comprehensiveness and accuracy of high-frequency characteristic analysis, so that the analysis result can accurately reflect the impedance change rule of the grounding grid in a high-frequency band, and a more reliable evaluation basis is provided for safe operation of a power system.

Description

Technical Field

[0001] This application relates to the fields of power systems and electrical measurement technology, and in particular to a method, apparatus and electronic equipment for high-frequency impedance analysis of grounding grids. Background Technology

[0002] In modern power systems, the grounding grid, as a core facility ensuring the safe and stable operation of power equipment and the protection of personnel, plays a crucial role in the reliability and safety of the power system. Grounding grids in large substations, transmission lines, and various industrial facilities are typically buried deep underground and are subject to long-term effects such as soil corrosion, mechanical stress, and natural aging, which can gradually degrade their grounding performance. This deterioration can not only lead to abnormal operation of power equipment but also trigger serious electrical accidents, threatening the stability of the power grid and personal safety. Furthermore, with the continuous expansion of power system scale and the increase in voltage levels, the grounding grid not only needs to effectively guide power frequency currents (50Hz / 60Hz) but also needs to withstand the impact of high-frequency transient currents such as lightning strikes and switching overvoltages. Therefore, the high-frequency impedance characteristic analysis of the grounding grid over a wide frequency range has become an important research direction for ensuring the safe operation of power systems.

[0003] Currently, the analysis of the high-frequency impedance characteristics of grounding grids mainly relies on two methods: one is the single-frequency measurement method based on sinusoidal excitation, which injects a sinusoidal signal of a single frequency into the grounding grid and measures its impedance value at a specific frequency. The other is the equivalent circuit analysis based on the lumped parameter model, which abstracts the grounding grid into an equivalent circuit composed of lumped resistors, inductors, and capacitors, and derives the high-frequency impedance parameters through power frequency measurement data.

[0004] However, existing methods still suffer from insufficient broadband coverage when analyzing the high-frequency impedance characteristics of grounding grids, resulting in inaccurate analysis of the high-frequency impedance characteristics of grounding grids. Summary of the Invention

[0005] The high-frequency impedance analysis method, apparatus, and electronic equipment for grounding grids provided in this application are intended to address the problem that existing methods still have insufficient broadband characteristic coverage when analyzing the high-frequency impedance characteristics of grounding grids, thereby improving the comprehensiveness and accuracy of high-frequency characteristic analysis and enabling the analysis results to accurately reflect the impedance variation law of the grounding grid in the high-frequency band.

[0006] In a first aspect, embodiments of this application provide a method for high-frequency impedance analysis of a grounding grid, including:

[0007] Obtain the triangular wave excitation signal, which is an even-symmetric triangular wave signal constructed based on the preset fundamental frequency and amplitude, and is used to inject it into the grounding grid;

[0008] Based on the triangular wave excitation signal, the response signals of the grounding grid at multiple measurement points are obtained. The response signals include high-frequency voltage signals and high-frequency current signals.

[0009] Based on the response signal and distributed parameter model, the input impedance spectrum of the grounding grid is determined. The input impedance spectrum is used to evaluate the high-frequency impedance characteristics of the grounding grid.

[0010] In one possible implementation, acquiring the triangular wave excitation signal includes:

[0011] An initial triangular wave excitation signal is generated based on the preset fundamental frequency and amplitude.

[0012] The initial triangular wave excitation signal is amplified by a power amplifier;

[0013] The amplified triangular wave excitation signal is injected into the grounding grid through a preset coupling device.

[0014] In one possible implementation, the preset coupling device is a high-frequency isolation transformer.

[0015] In one possible implementation, the response signals of the grounding grid at multiple measurement points are obtained based on the triangular wave excitation signal, including:

[0016] High-frequency voltage and high-frequency current signals under triangular wave excitation signals are collected by high-frequency voltage and high-frequency current sensors arranged at preset positions in the grounding grid. The preset positions include multiple preset measurement points.

[0017] The response signal includes a high-frequency voltage signal and a high-frequency current signal.

[0018] In one possible implementation, the high-frequency voltage sensor is a capacitive voltage divider; and / or, the high-frequency current sensor is a current sensor based on the Rogowski coil principle.

[0019] In one possible implementation, the input impedance spectrum of the grounding grid is determined based on the response signal and a distributed parameter model, including:

[0020] Perform a Fourier transform on the response signal to obtain the frequency domain response signal;

[0021] Based on the distributed parameter model, the characteristic impedance and propagation constant of the grounding grid are determined;

[0022] Based on the frequency domain response signal, characteristic impedance, and propagation constant, the input impedance of the grounding grid at the fundamental and harmonic frequencies of the triangular wave excitation signal is determined.

[0023] The input impedance spectrum of the grounding grid is generated based on the input impedance at the fundamental frequency and each harmonic frequency.

[0024] In one possible implementation, the distributed parameter model is a two-dimensional impedance spectrum calculation model, which is used to analyze the spatial distribution of high-frequency impedance characteristics in the plane of the grounding grid; in the two-dimensional impedance spectrum calculation model, the distributed parameters of the grounding grid are the same in the horizontal and vertical directions.

[0025] In one possible implementation, the method further includes:

[0026] Based on the two-dimensional impedance spectrum calculation model, the theoretical impedance spectrum of the grounding grid is generated.

[0027] The input impedance spectrum is compared and analyzed with the theoretical impedance spectrum to obtain the comparison results;

[0028] Based on the comparison results, the performance status and abnormal information of the grounding grid are determined. The abnormal information includes conductor breakage, corrosion or poor contact defects.

[0029] In one possible implementation, the input impedance spectrum of the grounding grid is generated based on the input impedance at the fundamental frequency and each harmonic frequency, including:

[0030] The input impedances at each frequency are combined to form an impedance-frequency curve, and the impedance-frequency curve is used as the input impedance spectrum; or, the input impedances at each frequency are accumulated to obtain the total impedance spectrum, and the total impedance spectrum is used as the input impedance spectrum.

[0031] In one possible implementation, before performing a Fourier transform on the response signal to obtain the frequency domain response signal, the method further includes:

[0032] The response signal is sampled based on a preset sampling frequency.

[0033] The sampled response signal is preprocessed, including denoising using wavelet transform and / or filtering using a Butterworth low-pass filter;

[0034] Accordingly, a Fourier transform is performed on the response signal to obtain the frequency domain response signal, including:

[0035] The frequency domain response signal is obtained by performing a Fourier transform on the preprocessed response signal.

[0036] In one possible implementation, the fundamental frequency range of the triangular wave excitation signal is 1 kHz to 1 MHz.

[0037] Secondly, embodiments of this application provide a grounding grid high-frequency impedance analysis device, comprising:

[0038] The signal generation and injection module is used to acquire the triangular wave excitation signal. The triangular wave excitation signal is an even-symmetric triangular wave signal constructed based on the preset fundamental frequency and amplitude, which is used to inject into the grounding grid.

[0039] The signal acquisition module is used to acquire the response signals of the grounding grid at multiple measurement points based on the triangular wave excitation signal. The response signals include high-frequency voltage signals and high-frequency current signals.

[0040] The data processing and analysis module is used to determine the input impedance spectrum of the grounding grid based on the response signal and distributed parameter model. The input impedance spectrum is used to evaluate the high-frequency impedance characteristics of the grounding grid.

[0041] Thirdly, embodiments of this application provide an electronic device, including: a memory and a processor;

[0042] The memory stores the instructions that the computer executes;

[0043] The processor executes computer execution instructions stored in memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0044] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0045] Fifthly, embodiments of this application provide a computer program product, including a computer program that, when executed, implements the first aspect and / or various possible implementations of the first aspect.

[0046] The high-frequency impedance analysis method, apparatus, and electronic equipment for grounding grids provided in this application acquire a triangular wave excitation signal. This triangular wave excitation signal is an even-symmetric triangular wave signal constructed based on a preset fundamental frequency and amplitude, which is injected into the grounding grid. Based on the triangular wave excitation signal, the response signals of the grounding grid at multiple measurement points are acquired. These response signals include high-frequency voltage signals and high-frequency current signals. Based on the response signals and a distributed parameter model, the input impedance spectrum of the grounding grid is determined. The input impedance spectrum is used to evaluate the high-frequency impedance characteristics of the grounding grid. The wideband characteristics of the triangular wave excitation signal achieve comprehensive coverage of the high-frequency impedance characteristics of the grounding grid over a wide frequency range, helping to accurately capture impedance abrupt changes in the high-frequency band and improve the accuracy of evaluating the high-frequency performance of the grounding grid. Furthermore, the application of the distributed parameter model enables a more accurate description of the distributed parameter effects of the grounding grid at high frequencies, further enhancing the analysis accuracy of the high-frequency impedance characteristics of the grounding grid. Furthermore, the acquisition and analysis of response signals from multiple measurement points can comprehensively reflect the consistency of impedance distribution within the grounding grid plane, which helps to identify local defects in the grounding grid and improve the accuracy of defect location. Thus, based on the input impedance spectrum determined by the response signals, the high-frequency impedance characteristics of the grounding grid can be evaluated more intuitively, which helps the power system to accurately assess the high-frequency transient performance of the grounding grid and provides strong support for the design, maintenance and fault diagnosis of the grounding grid. Attached Figure Description

[0047] 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.

[0048] Figure 1 Flowchart of the high-frequency impedance analysis method for grounding grids provided in this application Figure 1 ;

[0049] Figure 2 A schematic diagram of the triangular wave excitation provided in this application;

[0050] Figure 3 The triangular wave signal diagram provided in this application;

[0051] Figure 4 A comparison diagram of impedance spectrum amplitude characteristics provided in this application;

[0052] Figure 5 A comparison diagram of impedance spectrum phase characteristics provided in this application;

[0053] Figure 6 Flowchart of the high-frequency impedance analysis method for grounding grids provided in this application Figure 2 ;

[0054] Figure 7 A schematic diagram of the high-frequency impedance analysis device for grounding grids provided in this application;

[0055] Figure 8 A schematic diagram of the structure of the electronic device 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] First, let me explain the terms used in this application:

[0059] Grounding grid: refers to the conductor network in a power system used to conduct current into the earth, ensuring equipment safety and personnel protection.

[0060] High-frequency impedance characteristics refer to the comprehensive characteristics of electrical parameters such as resistance, inductance, and capacitance exhibited by the grounding grid under the action of high-frequency current.

[0061] Triangular wave excitation: refers to a periodic non-sinusoidal electrical signal excitation method. Its waveform presents a triangular change and contains rich harmonic components, which is used to excite the broadband characteristics of the grounding grid.

[0062] Fourier series decomposition is a mathematical method that decomposes a non-sinusoidal signal into a superposition of sinusoidal quantities of different frequencies.

[0063] Distributed parameter model: refers to a high-frequency equivalent circuit model that considers the distributed resistance, inductance, capacitance and conductance of the grounding grid conductor.

[0064] Fundamental frequency: refers to the basic frequency component of a triangular wave, which is the lowest frequency sine component in Fourier series decomposition. Other high-frequency components (harmonics) are all integer multiples of the fundamental frequency.

[0065] Skin effect: refers to the phenomenon that high-frequency current concentrates on the surface of a conductor, resulting in a decrease in the effective conductive area and an increase in resistance.

[0066] Complex dielectric constant: refers to a complex parameter that describes the dielectric properties of soil, including a real part and an imaginary part.

[0067] Equation: refers to a mathematical model that describes the frequency characteristics of the complex dielectric constant of soil and is used to calculate the distributed parameters of the grounding grid.

[0068] Amplitude-frequency characteristic: This refers to the characteristic curve of the amplitude of the grounding grid input impedance changing with frequency, reflecting the response law of the impedance magnitude at different frequencies. By collecting amplitude-frequency characteristics, the changing trends of parameters such as grounding grid resistance and inductance with frequency can be analyzed, and impedance abrupt change points in the high-frequency band can be identified.

[0069] Phase frequency characteristic: This refers to the characteristic curve of the phase of the grounding grid input impedance as a function of frequency, describing the relationship between the impedance phase angle and frequency. The phase frequency characteristic can help determine the distributed parameter effects of capacitance and inductance in the grounding grid, and is used together with the amplitude frequency characteristic for defect location analysis.

[0070] In existing technologies, single-frequency measurement methods based on sinusoidal excitation, due to their singular sinusoidal frequency, struggle to cover the dynamic response characteristics of the grounding grid across a wide frequency range, failing to effectively capture impedance abrupt changes at high frequencies. Furthermore, these methods typically assume a single-point impedance model for the grounding grid, neglecting the differences in distributed parameters between the horizontal and vertical directions, thus failing to reflect its complex structural characteristics. Equivalent circuit analysis methods based on lumped parameter models, however, do not consider the effects of distributed parameters in the grounding grid at high frequencies, such as mutual inductance between conductors and the dispersion characteristics of the soil, leading to significant deviations between the model and actual physical laws. Simultaneously, these models simplify the grounding grid to a one-dimensional network structure, making it impossible to analyze the non-uniformity of impedance distribution in the plane and difficult to identify local defects.

[0071] It is evident that existing technologies have significant shortcomings in analyzing the high-frequency impedance characteristics of grounding grids, particularly in terms of broadband coverage, distributed parameter modeling, spatial distribution analysis, and anti-interference capabilities. The lack of broadband coverage is a major issue, as current methods can only measure impedance characteristics at limited frequency points and cannot fully reflect the broadband response of the grounding grid during high-frequency transient processes. This results in inaccurate analysis of the high-frequency impedance characteristics of the grounding grid, failing to meet the urgent needs of power systems for comprehensive evaluation and fault diagnosis of the high-frequency characteristics of the grounding grid.

[0072] To address the aforementioned issues, this application provides a method, apparatus, and electronic device for high-frequency impedance analysis of grounding grids. This method considers the limitation of traditional single-frequency sinusoidal excitation in covering a wide frequency range and employs an even-symmetric triangular wave signal constructed based on a preset fundamental frequency and amplitude as the excitation source. The triangular wave signal possesses rich odd-order harmonic components, naturally covering a wide frequency band from low to high frequencies, providing a foundation for comprehensively capturing the high-frequency response of the grounding grid. Simultaneously, to more realistically reflect the actual operating state of the grounding grid, response signals, including high-frequency voltage and current signals, are acquired at multiple measurement points within the grounding grid. This takes into account the lateral and longitudinal distribution differences of the grounding grid in the plane, avoiding the limitations of traditional single-point measurements. Furthermore, the acquired response signals are analyzed in depth using a distributed parameter model to determine the input impedance spectrum of the grounding grid. The distributed parameter model can more accurately describe the complex electrical characteristics of the grounding grid at high frequencies, such as the skin effect and soil dispersion, thereby ensuring the accuracy and reliability of the high-frequency impedance characteristic analysis of the grounding grid.

[0073] 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.

[0074] The execution subject of the high-frequency impedance analysis method for grounding grids provided in this application embodiment can be a computing device such as a server or server cluster. The server can be a mobile phone, computer, tablet, or other device. This application embodiment does not impose any particular restrictions on the implementation method of the execution subject, as long as the execution subject can acquire a triangular wave excitation signal. The triangular wave excitation signal is an even-symmetric triangular wave signal constructed based on a preset fundamental frequency and amplitude, used for injection into the grounding grid. Based on the triangular wave excitation signal, the response signals of the grounding grid at multiple measurement points are acquired. The response signals include high-frequency voltage signals and high-frequency current signals. Based on the response signals and the distributed parameter model, the input impedance spectrum of the grounding grid is determined. The input impedance spectrum is used to evaluate the high-frequency impedance characteristics of the grounding grid.

[0075] Figure 1 Flowchart of the high-frequency impedance analysis method for grounding grids provided in this application Figure 1 The execution entity of this method can be a system server or other server that stores the high-frequency impedance analysis method for grounding grids. This embodiment does not impose any special limitations on this. Figure 1 As shown, the method may include:

[0076] S101. Obtain the triangular wave excitation signal. The triangular wave excitation signal is an even-symmetric triangular wave signal constructed based on the preset fundamental frequency and amplitude, which is used to inject into the grounding grid.

[0077] In this step, the triangular wave excitation signal can be a periodic waveform signal, whose waveform is linear in both positive and negative directions, symmetrical about the time axis, and rich in odd harmonic components, making it suitable for broadband excitation. An even-symmetric triangular wave signal refers to a triangular wave signal that is symmetrical about the time axis, ensuring that the signal has the same shape in both positive and negative half-cycles, which helps reduce even harmonic interference.

[0078] Furthermore, even-symmetric triangular wave signals can be generated based on preset fundamental frequency and amplitude.

[0079] In some examples, a signal generator can be used, set to a fundamental frequency of 1kHz and an amplitude of 5V, to generate an even-symmetric triangular wave signal. Alternatively, a triangular wave signal can be generated using software algorithms (such as digital signal processing) and output to a power amplifier to drive the grounding grid.

[0080] S102. Based on the triangular wave excitation signal, obtain the response signals of the grounding grid at multiple measurement points. The response signals include high-frequency voltage signals and high-frequency current signals.

[0081] The response signal refers to the voltage and current signals generated by the grounding grid after being subjected to an excitation signal. High-frequency voltage and current signals refer to the high-frequency components contained in the response signal, used to analyze the high-frequency characteristics of the grounding grid.

[0082] In some embodiments, high-frequency voltage and high-frequency current signals can be acquired simultaneously or sequentially at multiple preset measurement points in the grounding grid. For example, a high-frequency voltmeter and a high-frequency current clamp can be used to perform measurements at multiple locations such as the inlet, intermediate nodes, and ends of the grounding grid. Alternatively, a multi-channel data acquisition system can be used to simultaneously record the response signals of multiple measurement points, ensuring data synchronization and accuracy.

[0083] S103. Based on the response signal and distributed parameter model, determine the input impedance spectrum of the grounding grid. The input impedance spectrum is used to evaluate the high-frequency impedance characteristics of the grounding grid.

[0084] The input impedance spectrum reflects the input impedance value of the grounding grid at different frequencies and is used to evaluate its high-frequency impedance characteristics.

[0085] The collected response signal can be combined with a distributed parameter model to obtain the input impedance spectrum of the grounding grid through calculation and analysis. For example, using circuit analysis software (such as MATLAB / Simulink, PSpice, etc.), the response signal data can be imported into the distributed parameter model for frequency domain analysis to obtain the input impedance spectrum. Alternatively, specialized grounding analysis software can be used to calculate the input impedance spectrum of the grounding grid based on the response signal and soil parameters.

[0086] The high-frequency impedance analysis method for grounding grids provided in this application achieves broadband excitation of the grounding grid by acquiring an even-symmetric triangular wave excitation signal rich in odd harmonics; it comprehensively captures the spatial distribution characteristics of the grounding grid by acquiring response signals at multiple measurement points; and it accurately determines the input impedance spectrum of the grounding grid by combining a distributed parameter model. This method effectively solves the problems of insufficient broadband coverage and incomplete consideration of spatial distribution characteristics in traditional methods, significantly improving the accuracy and comprehensiveness of the high-frequency impedance characteristic analysis of the grounding grid, and providing strong support for the grounding design, maintenance, and fault diagnosis of power systems.

[0087] Based on the above embodiments, the method for obtaining the triangular wave excitation signal described in S101 may include: generating an initial triangular wave excitation signal based on a preset fundamental frequency and amplitude; amplifying the initial triangular wave excitation signal through a power amplifier; and injecting the amplified triangular wave excitation signal into the grounding grid through a preset coupling device.

[0088] In this embodiment, the power amplifier can be an electronic device used to amplify the power of a weak input signal (such as an initial triangular wave excitation signal) to drive a subsequent load (such as a grounding grid) so that it can obtain sufficient energy to respond. It can increase the voltage and current amplitude of the signal to meet the signal strength requirements for injection into the grounding grid.

[0089] The pre-coupled device is used to safely and effectively inject the amplified triangular wave excitation signal into the grounding grid. It can provide electrical isolation and impedance matching, ensuring that the excitation signal can be successfully transmitted to the grounding grid while avoiding adverse effects on the signal source and other equipment.

[0090] In some examples, based on a preset fundamental frequency and amplitude, an initial even-symmetric triangular wave excitation signal is generated using a signal generator or software algorithm; the generated initial triangular wave excitation signal is input into a power amplifier, which amplifies the signal to give it sufficient strength; the amplified triangular wave excitation signal is injected into the grounding grid through a preset coupling device to prepare for obtaining the response signal of the grounding grid.

[0091] Optionally, a linear power amplifier can be selected, whose operating frequency range can cover the frequency range of the triangular wave excitation signal. For example, if the fundamental frequency of the triangular wave excitation signal is 1kHz, considering harmonic components, the operating frequency range of the power amplifier can be set to DC-100MHz. The initial triangular wave excitation signal is input into the power amplifier, and the amplification factor is adjusted to achieve the desired amplitude of the output signal, such as 10V. Alternatively, a switching-mode power amplifier can be used, which has higher efficiency and is suitable for scenarios with high power requirements. Based on the parameters of the initial triangular wave excitation signal, the operating mode and parameters of the switching-mode power amplifier are set to achieve signal amplification.

[0092] Alternatively, a transformer can be used as a coupling device. The amplified triangular wave excitation signal is connected to the primary side of the transformer, and the signal is transmitted to the secondary side and then connected to the grounding grid through the electromagnetic coupling effect of the transformer. The transformer turns ratio is designed appropriately to meet the signal injection requirements. Alternatively, capacitive coupling can be used, connecting the amplified signal to the grounding grid through a capacitor. Choosing an appropriate capacitor value ensures that the signal can be effectively coupled to the grounding grid, while also providing some filtering and isolation.

[0093] In some specific examples, the triangular wave is a periodic non-sinusoidal component that can be expanded into a Fourier series, that is, decomposed into a series of sinusoidal quantities with different frequencies that are superimposed, which includes the fundamental wave and a series of odd harmonics (such as the 3rd, 5th, 7th, etc.).

[0094] Based on period Amplitude The triangular wave excitation signal is as follows Figure 2 As shown, it can be represented as:

[0095] ;

[0096] For a triangular wave signal, the wavelengths corresponding to each frequency component still satisfy... ( The speed at which a signal propagates in the transmission medium. (Frequency), i.e., fundamental frequency Corresponding wavelength , Subharmonic frequency ,in, Its corresponding wavelength .

[0097] For an even-symmetric triangular wave, after Fourier series decomposition, it can be expressed as:

[0098] ;

[0099] in, For the amplitude of the triangular wave, The fundamental frequency of the triangular wave ( , (For the period).

[0100] For an odd-symmetric triangular wave, the decomposition represents a superposition of sine functions. The difference between the two is that, due to the 90° difference between the sine and cosine functions, the even-symmetric triangular wave lags behind the odd-symmetric triangular wave by 90° and has different harmonic amplitudes. To simplify the DC term processing in transmission line analysis and better reflect actual systems, this embodiment uses an even-symmetric triangular wave, such as... Figure 3 As shown.

[0101] By introducing a power amplifier to amplify the initial signal, sufficient signal strength is ensured to be injected into the grounding grid. The use of a pre-set coupling device enables safe and effective signal injection, avoids interference and loss during signal transmission, and ensures that the grounding grid can obtain an accurate and effective excitation signal. This lays a solid foundation for the subsequent accurate acquisition of the grounding grid's response signal and analysis of its high-frequency impedance characteristics.

[0102] In practical applications, different coupling devices have varying impacts on signal transmission quality and stability. Inappropriate selection of the coupling device can lead to signal distortion, interference, and other problems, affecting subsequent analysis of the high-frequency impedance characteristics of the grounding grid. Therefore, based on the above embodiments, the coupling device can be a high-frequency isolation transformer.

[0103] A high-frequency isolation transformer is a transformer that operates in the high-frequency band and provides electrical isolation between the input and output. It transmits the input high-frequency signal to the output terminal through the principle of electromagnetic induction, while isolating the DC path between the input and output circuits, effectively preventing electrical interference between different circuits. It also performs voltage transformation and impedance matching, enabling the signal to be better adapted to subsequent circuits or loads (such as grounding grids).

[0104] In one example, during the process of injecting the amplified triangular wave excitation signal into the grounding grid, the triangular wave excitation signal amplified by the power amplifier is connected to the primary winding of the high-frequency isolation transformer. The high-frequency isolation transformer couples the signal to the secondary winding through electromagnetic induction, and then connects the secondary winding to the grounding grid, thereby realizing the injection of the amplified triangular wave excitation signal into the grounding grid through the high-frequency isolation transformer.

[0105] The turns ratio of the high-frequency isolation transformer can be selected based on the signal frequency. For example, if the main frequency components of the amplified triangular wave excitation signal are concentrated in the 10kHz-1MHz range, a high-frequency isolation transformer with an operating frequency range covering this band can be selected. For instance, a certain model of high-frequency isolation transformer operates in the 10kHz-5MHz range. The amplified signal is connected to the primary side of this transformer, and the secondary side is connected to the grounding grid. Alternatively, it can be selected based on impedance matching requirements: when the input impedance of the grounding grid does not match the output impedance of the amplifier, a high-frequency isolation transformer with a suitable turns ratio can be used to achieve impedance matching. For example, if the input impedance of the grounding grid is 50Ω and the output impedance of the amplifier is 100Ω, a turns ratio of [missing value] can be selected. The high-frequency isolation transformer enables the signal to be effectively transmitted to the grounding grid.

[0106] By defining the preset coupling device as a high-frequency isolation transformer, its high-frequency characteristics can better adapt to the high-frequency components in the triangular wave excitation signal, ensuring the accuracy of signal transmission. At the same time, its isolation function effectively avoids electrical interference between the signal source and the grounding grid, improving the stability and reliability of signal injection, and providing a strong guarantee for the subsequent accurate acquisition of the grounding grid response signal and precise analysis of high-frequency impedance characteristics.

[0107] In practice, to accurately analyze the high-frequency impedance characteristics of a grounding grid, it is necessary to accurately measure the high-frequency voltage and current signals at multiple measurement points. Selecting appropriate measurement tools and effectively acquiring these signals are technical problems that need to be solved. Therefore, based on the above embodiments, the method described in S102 for obtaining the response signals of a grounding grid at multiple measurement points based on a triangular wave excitation signal may include: acquiring high-frequency voltage and current signals under a triangular wave excitation signal by using high-frequency voltage and current sensors arranged at preset locations on the grounding grid, wherein the preset locations include multiple preset measurement points; and wherein the response signals include high-frequency voltage and high-frequency current signals.

[0108] Among them, a high-frequency voltage sensor is a device that can convert high-frequency voltage signals into measurable signals (such as small voltage signals). It has a high frequency response range, accurately sensing changes in high-frequency voltage on the grounding grid and converting them into a form that subsequent data acquisition equipment can process. A high-frequency current sensor is a device used to measure high-frequency current, typically operating based on the principle of electromagnetic induction. When a high-frequency current flows through the grounding grid, the high-frequency current sensor can sense the corresponding electromotive force or current signal, thereby achieving the measurement of that high-frequency current.

[0109] In some examples, high-frequency voltage sensors and high-frequency current sensors are installed at multiple pre-defined measurement points on the grounding grid. After a triangular wave excitation signal is injected into the grounding grid, the high-frequency voltage sensors and high-frequency current sensors start working and collect the high-frequency voltage signals and high-frequency current signals of the corresponding measurement points, respectively.

[0110] It should be noted that for grounding grids of different sizes and characteristics, high-frequency voltage and current sensors with appropriate ranges and accuracies can be selected. For example, for large industrial grounding grids, the high-frequency voltage and current may be large, so sensors with a wider range should be selected; while for grounding grids of small precision equipment, high-precision sensors can be selected. The selected sensors should be installed and fixed at the preset measurement point locations, ensuring good contact between the sensor and the grounding grid.

[0111] During signal acquisition, a multi-channel data acquisition system can be used, connecting various high-frequency voltage and current sensors to the data acquisition device. Simultaneously with the injection of a triangular wave excitation signal, the data acquisition device collects and stores the signals output by the sensors according to a set sampling frequency. For example, the sampling frequency can be set to 5-10 times the highest frequency component of the triangular wave excitation signal to ensure accurate signal acquisition.

[0112] By explicitly employing high-frequency voltage and current sensors to collect response signals at multiple preset measurement points in the grounding grid, a specific method is provided for accurately obtaining high-frequency voltage and current information of the grounding grid under triangular wave excitation. This ensures that the collected signals can truly reflect the high-frequency electrical characteristics of the grounding grid, laying a reliable foundation for subsequent analysis of the high-frequency impedance spectrum of the grounding grid based on these signals.

[0113] However, in practical applications, different types of sensors differ in performance and applicable range. Selecting the appropriate sensor type is crucial for accurately measuring the high-frequency voltage and current signals of the grounding grid. Therefore, based on the above embodiments, the high-frequency voltage sensor can be a capacitive voltage divider type; and / or, the high-frequency current sensor can be a current sensor based on the Rogowski coil principle.

[0114] Among them, the capacitive voltage divider sensor is a sensor that measures voltage using the principle of capacitive voltage division. It consists of multiple capacitors connected in series to form a voltage divider circuit. By measuring the voltage across some of the capacitors, the measured voltage value is calculated based on the voltage division ratio. This type of sensor has advantages such as good high-frequency characteristics, fast response speed, and resistance to saturation, making it suitable for measuring high-frequency voltage signals.

[0115] A Rogowski coil is a hollow toroidal coil. When a measured current passes through its center, an induced electromotive force (EMF) is generated across the coil according to the law of electromagnetic induction. By processing this induced EMF through an integrating circuit, an output signal proportional to the measured current can be obtained. Current sensors based on the Rogowski coil principle have advantages such as a wide measurement range, a large frequency response range, no magnetic saturation phenomenon, and convenient installation, and can be used for high-frequency current measurement.

[0116] In some examples, for capacitive voltage divider sensors, they can be correctly connected in parallel across the measurement points of the grounding grid where high-frequency voltage needs to be measured. Based on the voltage division ratio, the voltage signals on the collected capacitors are converted to obtain the actual high-frequency voltage signal.

[0117] For current sensors based on the Rogowski coil principle, the Rogowski coil can be placed on the conductor of the grounding grid where the high-frequency current to be measured is to sense the magnetic field generated by the change of high-frequency current in the conductor, thereby generating an induced electromotive force at both ends of the Rogowski coil. The signal is then processed by an integrating circuit to obtain a signal proportional to the high-frequency current.

[0118] By clearly defining the high-frequency voltage sensor as a capacitive voltage divider and the high-frequency current sensor as a current sensor based on the Rogowski coil principle, the advantages of these two sensors can be fully utilized to more accurately and reliably measure the high-frequency voltage and current signals of the grounding grid, thereby further improving the accuracy and reliability of the high-frequency impedance analysis method for the grounding grid.

[0119] It is understandable that the electrical characteristics of a grounding grid vary at different frequencies. To fully understand these characteristics, it is necessary to accurately obtain its input impedance at different frequencies. Therefore, how to analyze the input impedance spectrum of the grounding grid from the collected signals is a problem that needs to be solved. Based on this, the method for determining the input impedance spectrum of a grounding grid based on the response signal and distributed parameter model described in S103, building upon the above embodiments, may include: performing a Fourier transform on the response signal to obtain a frequency domain response signal; determining the characteristic impedance and propagation constant of the grounding grid based on the distributed parameter model; determining the input impedance of the grounding grid at the fundamental and harmonic frequencies of the triangular wave excitation signal based on the frequency domain response signal, characteristic impedance, and propagation constant; and generating the input impedance spectrum of the grounding grid based on the input impedance at the fundamental and harmonic frequencies.

[0120] In this embodiment, the Fourier transform is a mathematical transformation method that converts a time-domain signal into a frequency-domain signal. In the field of signal processing, many signal features that are difficult to analyze in the time domain can be more clearly displayed in the frequency domain. Through the Fourier transform, the acquired time-varying response signal can be decomposed into a combination of sine and cosine components of different frequencies, thereby obtaining a frequency-domain response signal, which can then be analyzed and processed in the frequency domain.

[0121] The distributed parameter model is used to describe the electrical characteristics of a grounding grid. This model considers the distributed parameters of the grounding grid conductors, such as resistance, inductance, and capacitance, which vary with location. Unlike the lumped parameter model, the distributed parameter model more accurately reflects the electrical behavior of the grounding grid in actual operation, especially at high frequencies where the influence of distributed parameters is more significant.

[0122] Characteristic impedance is an important parameter of distributed parameter transmission lines (such as grounding grid conductors). It represents the ratio of voltage to current when electromagnetic waves propagate on the transmission line, reflecting the characteristics of the transmission line itself, and is related to factors such as the geometry of the transmission line, the material, and the surrounding medium.

[0123] The propagation constant is also a parameter describing the propagation characteristics of electromagnetic waves on a transmission line. It can consist of two parts: the attenuation constant and the phase constant. The attenuation constant indicates the degree of amplitude attenuation during the propagation of the electromagnetic wave, while the phase constant indicates the change in the phase of the electromagnetic wave.

[0124] An input impedance spectrum is a collection of the input impedances of a grounding grid at different frequencies, plotted as a curve or graph with frequency on the x-axis and input impedance on the y-axis. The input impedance spectrum provides a visual understanding of how the electrical characteristics of the grounding grid change at different frequencies.

[0125] In some examples, the Fourier transform algorithm is used to process the collected grounding grid response signals (high-frequency voltage signals and high-frequency current signals) at multiple measurement points, converting them from the time domain to the frequency domain to obtain the frequency domain response signal. Based on the pre-established grounding grid distributed parameter model, combined with the actual structure, materials, and other parameters of the grounding grid, the characteristic impedance and propagation constant of the grounding grid are calculated. Using the obtained frequency domain response signal, characteristic impedance, and propagation constant, the input impedance of the grounding grid at the fundamental and harmonic frequencies of the triangular wave excitation signal is determined through specific mathematical formulas and calculation methods. The calculated input impedances at the fundamental and harmonic frequencies are then organized and plotted in frequency order to generate the input impedance spectrum of the grounding grid.

[0126] The Fourier transform can be implemented using specialized signal processing software, such as the Fast Fourier Transform (FFT) function in MATLAB. By importing the acquired response signal data into the software, setting appropriate parameters such as sampling frequency and number of transform points, and running the FFT function, the frequency domain response signal can be obtained.

[0127] Alternatively, a hardware-implemented Fourier transform module can be used. For example, some digital signal processor (DSP) chips have built-in FFT functions. The response signal is input into the DSP chip, and the Fourier transform is completed by programming the chip to output the frequency domain response signal.

[0128] Input impedance calculation and impedance spectrum generation can be performed using the obtained frequency domain response signal, characteristic impedance, and propagation constant. Based on relevant formulas in transmission line theory, a calculation program can be written to calculate the input impedance at various frequencies. The calculation results are then imported into plotting software such as Origin, and the input impedance spectrum of the grounding grid is plotted with frequency on the x-axis and input impedance on the y-axis.

[0129] By converting the response signal to the frequency domain using Fourier transform and combining it with the distributed parameter model to calculate the characteristic parameters, the input impedance of the grounding grid at different frequencies is determined and the input impedance spectrum is generated. This provides comprehensive and detailed data support for accurately analyzing the high-frequency electrical characteristics of the grounding grid and helps to gain a deeper understanding of the performance of the grounding grid.

[0130] The distributed parameter model mentioned in the above embodiments is rather broad. In actual analysis of the high-frequency impedance characteristics of grounding grids, a more specific model that better reflects the spatial distribution characteristics within the grounding grid plane is needed to gain a deeper understanding of the impedance at different locations. Therefore, based on the above embodiments, the distributed parameter model is a two-dimensional impedance spectrum calculation model, used to analyze the spatial distribution of high-frequency impedance characteristics within the grounding grid plane. In the two-dimensional impedance spectrum calculation model, the distributed parameters of the grounding grid are the same in both the horizontal and vertical directions.

[0131] The two-dimensional impedance spectrum calculation model is a mathematical model used to analyze the spatial distribution of high-frequency impedance characteristics of grounding grids in a plane. It treats the grounding grid as a two-dimensional planar structure, taking into account the distribution of electrical parameters of the grounding grid in the horizontal (e.g., horizontal direction) and vertical (e.g., vertical direction, which can be understood as another horizontal direction in the context of the grounding grid plane). By establishing corresponding mathematical equations and calculation methods, it is possible to calculate the high-frequency impedance characteristics of the grounding grid at different locations and display its spatial distribution law in a two-dimensional form.

[0132] In some embodiments, a two-dimensional impedance spectrum calculation model can be constructed based on the actual planar layout and structural parameters of the grounding grid. The dimensions of the grounding grid in the horizontal and vertical directions, conductor spacing, conductor material properties, and other parameters are determined in the model, assuming that the distribution parameters of the grounding grid are the same in both directions. Then, the distribution parameters of the grounding grid conductors, such as resistance, inductance, and capacitance, are set according to the model requirements. Since the horizontal and vertical distribution parameters are assumed to be the same, the calculation process can be simplified when setting the parameters. Finally, appropriate mathematical calculation methods, such as the finite difference method and the finite element method, are used to solve the two-dimensional impedance spectrum calculation model, analyze the spatial distribution of high-frequency impedance characteristics within the grounding grid plane, and obtain relevant information such as impedance values ​​at different locations.

[0133] In some examples, if only the horizontal grounding grid is considered, and vertical grounding electrodes and natural grounding electrodes are ignored; the mutual inductance and mutual resistance parameters between conductors are averaged to a single conductor; the distributed parameters in the transverse (x-direction) and longitudinal (y-direction) directions are the same, and weak coupling between conductors is ignored, then the two-dimensional input impedance of the grounding grid along the x-direction and y-direction is:

[0134] ;

[0135] in, The load reflection coefficient, For wave impedance, Let be the propagation constant. and All of these depend on the characteristics of the grounding grid itself. By measuring the input impedance frequency response characteristics of the grounding grid, 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 spectrum are used to obtain the differences in amplitude and phase frequency characteristics of the grounding grid impedance spectrum.

[0136] Substituting the triangular wave excitation function into the grounding grid impedance spectrum calculation, we obtain the frequency of each harmonic. The input impedance is:

[0137] ;

[0138] in, Given the load impedance, characteristic impedance, and propagation coefficient, they can be expressed as:

[0139] .

[0140] By employing a two-dimensional impedance spectrum calculation model and assuming that the distribution parameters of the grounding grid are the same in the horizontal and vertical directions, the spatial distribution of high-frequency impedance characteristics in the grounding grid plane can be accurately analyzed, while the calculation process of the model is simplified and the calculation efficiency is improved.

[0141] In practical applications, simply obtaining the input impedance spectrum is insufficient; it is also necessary to compare it with the theoretical value to accurately determine the performance status of the grounding grid and whether any anomalies exist. Therefore, based on the above embodiments, this method may further include: generating the theoretical impedance spectrum of the grounding grid based on a two-dimensional impedance spectrum calculation model; comparing and analyzing the input impedance spectrum with the theoretical impedance spectrum to obtain the comparison results; and determining the performance status and anomaly information of the grounding grid based on the comparison results, including conductor breakage, corrosion, or poor contact defects.

[0142] Among them, the theoretical impedance spectrum is a set of input impedances of the grounding grid at different frequencies obtained by theoretical calculation based on the two-dimensional impedance spectrum calculation model under ideal conditions (assuming that the grounding grid has no defects and the materials are uniform, etc.). It reflects the relationship between the electrical characteristics of the grounding grid under normal conditions and the frequency.

[0143] Comparative analysis refers to the process of comparing and analyzing various parameters (such as the magnitude of impedance value, trend of change, impedance at a specific frequency point, etc.) between the actual measured and generated input impedance spectrum and the theoretical impedance spectrum, with the aim of finding the differences between the two.

[0144] Performance status can refer to the current working performance of the grounding grid, such as whether its conductivity, current dissipation capacity, etc. are within the normal range.

[0145] Abnormal information can be a problem reflected in the grounding grid when there is a difference between the input impedance spectrum and the theoretical impedance spectrum. For example, a broken conductor will interrupt the conductive path in that part and change the local electrical characteristics; corrosion will reduce the cross-sectional area of ​​the conductor and increase the resistance; poor contact will increase the contact resistance and affect the conduction of current.

[0146] In this embodiment, based on the pre-constructed two-dimensional impedance spectrum calculation model, combined with the grounding grid's design parameters and material properties, appropriate calculation methods are used to calculate the theoretical input impedance of the grounding grid at the fundamental and harmonic frequencies, thereby generating a theoretical impedance spectrum. The actual input impedance spectrum and the theoretical impedance spectrum are placed in the same coordinate system, and their impedance values ​​and trends at various frequency points are compared. Numerical calculation methods can be used to calculate the differences and relative errors between the two at various frequency points to quantitatively analyze the differences. Finally, based on the results of the comparative analysis, the performance status of the grounding grid is determined. If the difference is within a reasonable range, the grounding grid is considered to be performing normally; if the difference exceeds a reasonable range, the characteristics of the difference are further analyzed to identify any abnormal information, such as determining whether the problem is conductor breakage, corrosion, or poor contact based on the impedance changes at specific frequency points.

[0147] In some examples, when a local conductor breaks, corrodes, or has poor contact, a sudden change in load impedance causes a change in the load reflection coefficient. Anomalies are identified by comparing the frequency domain deviations between measured and theoretical impedance spectra to assess the performance of the grounding grid. For example... Figure 4 and Figure 5 As shown, by analyzing the impedance spectrum amplitude characteristic comparison diagram and the impedance spectrum phase characteristic comparison diagram, abnormal fault points can be identified.

[0148] By comparing and analyzing the actual generated input impedance spectrum with the theoretical impedance spectrum obtained based on the two-dimensional impedance spectrum calculation model, the performance status of the grounding grid can be accurately determined, and abnormal information such as conductor breakage, corrosion or poor contact can be detected in a timely manner. This provides clear guidance for the maintenance and troubleshooting of the grounding grid, and improves the safety and reliability of the grounding grid operation.

[0149] Based on the above embodiments, a method for generating the input impedance spectrum of a grounding grid based on the input impedance at the fundamental frequency and each harmonic frequency may include: combining the input impedance at each frequency into an impedance frequency curve and using the impedance frequency curve as the input impedance spectrum; or, accumulating the input impedance at each frequency to obtain a total impedance spectrum and using the total impedance spectrum as the input impedance spectrum.

[0150] In this embodiment, the impedance-frequency curve can be a curve plotted with frequency on the horizontal axis and input impedance on the vertical axis. It visually demonstrates the change in input impedance of the grounding grid at different frequencies. By observing the shape, trend, and other characteristics of the curve, the changing pattern of the electrical characteristics of the grounding grid with frequency can be understood.

[0151] In one example, input impedance data at the fundamental and harmonic frequencies can be collected; a coordinate system can be established with frequency as the horizontal axis and input impedance as the vertical axis; the input impedance value corresponding to each frequency can be marked in the coordinate system, and then these points can be connected with a smooth curve to form an impedance-frequency curve, which can be used as the input impedance spectrum.

[0152] In some examples, the variation of the real part (resistance) and imaginary part (reactance) of the grounding grid impedance with frequency is further analyzed. By plotting the impedance frequency response curve, the changes in the resistance, inductance, and capacitance characteristics of the grounding grid in the high-frequency range are visually displayed, thereby providing a deeper understanding of the high-frequency electrical performance of the grounding grid.

[0153] The total impedance spectrum is a comprehensive impedance characterization obtained by summing the input impedance at the fundamental frequency and each harmonic frequency. It reflects the impedance characteristics of the grounding grid under the influence of multiple frequency components as a whole. Unlike the impedance frequency curve, which shows the impedance at each frequency separately, the total impedance spectrum provides a concept of a cumulative impedance value.

[0154] In one example, the input impedance values ​​at the fundamental frequency and each harmonic frequency can be determined; according to a certain mathematical accumulation rule (usually a simple numerical addition), the input impedance values ​​at these different frequencies are accumulated and calculated; the total impedance value obtained after accumulation is taken as the total impedance spectrum and regarded as a form of the input impedance spectrum.

[0155] In some examples, the impedance spectra at each harmonic frequency are summed to obtain the total impedance spectrum of the grounding grid:

[0156] ;

[0157] in, Indicates frequency at Discrete components at the location, 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 this formula.

[0158] Two methods for generating input impedance spectra are used: the impedance-frequency curve method clearly displays the details of how the input impedance changes with frequency, facilitating the analysis of the frequency characteristics of the grounding grid; the total impedance spectrum method provides a comprehensive characterization of the impedance as a whole. These two methods offer flexible options for grounding grid impedance analysis under different requirements, improving the efficiency and relevance of the analysis.

[0159] Based on the above embodiments, before performing a Fourier transform on the response signal to obtain the frequency domain response signal, the method may further include: sampling the response signal based on a preset sampling frequency; preprocessing the sampled response signal, the preprocessing including denoising using wavelet transform and / or filtering using a Butterworth low-pass filter; correspondingly, performing a Fourier transform on the response signal to obtain the frequency domain response signal includes: performing a Fourier transform on the preprocessed response signal to obtain the frequency domain response signal.

[0160] In this embodiment, the preset sampling frequency refers to the sampling rate pre-set before sampling the response signal, which determines the number of samples of the response signal collected per unit time. The selection of the sampling frequency needs to be determined based on the frequency components of the response signal and the accuracy requirements of subsequent analysis.

[0161] Wavelet transform is a time-frequency analysis method that effectively analyzes the local features of a signal by decomposing it into wavelet spaces of different scales. In signal denoising, wavelet transform can separate and remove noise components from the signal based on the differences in characteristics between the signal and noise at different scales.

[0162] A Butterworth low-pass filter is an electronic filter that features the flattest amplitude response within its passband. Low-pass filters allow low-frequency signals to pass while attenuating high-frequency signals. When processing the response signal of a grounding grid, a Butterworth low-pass filter can remove high-frequency noise interference while retaining useful low-frequency information.

[0163] In some examples, the response signal measured from the grounding grid can be sampled at equal time intervals according to a pre-set sampling frequency, converting the continuous analog response signal into a discrete digital signal. During preprocessing: (1) Select appropriate wavelet basis functions and decomposition levels, perform wavelet decomposition on the sampled response signal, set thresholds to process the wavelet coefficients according to the distribution characteristics of the signal and noise on the wavelet coefficients, remove the wavelet coefficients corresponding to noise, and then obtain the denoised signal through wavelet reconstruction. (2) Determine the parameters such as the order and cutoff frequency of the Butterworth low-pass filter, and design the filter. Input the sampled response signal into the designed filter, the filter filters the signal, removes high-frequency noise, and outputs the filtered signal. It should be noted that preprocessing can choose to use only wavelet transform for denoising, only Butterworth low-pass filter for filtering, or both at the same time. Finally, perform Fourier transform on the preprocessed response signal to convert the time-domain response signal into a frequency-domain response signal in order to analyze the frequency components and characteristics of the response signal.

[0164] In one example, during sampling, the data acquisition system can employ high-speed sampling technology with a sampling frequency of no less than 10MHz to ensure accurate acquisition of the high-frequency response signal details of the grounding grid under triangular wave excitation. Because the waveform changes relatively slowly, it is easier to accurately capture signal characteristics at the same sampling frequency. Simultaneously, the data acquisition system has anti-interference capabilities, effectively suppressing the impact of external high-frequency interference signals on the acquired data through a combination of hardware filtering and software algorithms.

[0165] In actual measurements of the grounding grid response signal, various noises are often introduced due to factors such as the measurement environment and equipment. These noises affect the accuracy and reliability of the frequency domain response signal obtained by subsequent Fourier transform. Therefore, sampling the response signal based on a preset sampling frequency ensures the standardization and accuracy of signal acquisition. Preprocessing methods such as wavelet transform denoising and Butterworth low-pass filtering effectively remove noise interference from the response signal, making the frequency domain response signal obtained after Fourier transform more accurate and clearer. This provides a reliable data foundation for subsequent analysis of grounding grid characteristics based on the frequency domain response signal.

[0166] Based on the above embodiments, the fundamental frequency range of the triangular wave excitation signal can be from 1 kHz to 1 MHz.

[0167] Furthermore, when performing high-frequency impedance analysis of the grounding grid using a triangular wave excitation signal, it is necessary to ensure that its fundamental frequency is within the range of 1kHz to 1MHz. During the experimental preparation phase, based on the specific test requirements and the characteristics of the grounding grid, a suitable fundamental frequency value is selected from this frequency range to generate the triangular wave excitation signal. For example, if the grounding grid is small, a lower fundamental frequency may be chosen; if the grounding grid is more complex or requires more detailed analysis, a higher fundamental frequency is selected. Then, this generated triangular wave excitation signal with a specific fundamental frequency is applied to the grounding grid.

[0168] By defining the fundamental frequency range of the triangular wave excitation signal, we can ensure that the triangular wave excitation signal can effectively excite the grounding grid to generate a measurable response signal, and also enable the measuring equipment to operate within a reasonable performance range, reducing noise interference, thereby improving the accuracy and reliability of obtaining grounding grid characteristic information.

[0169] Therefore, the high-frequency impedance analysis method for grounding grids provided in this application can be applied to high-frequency performance evaluation and defect diagnosis scenarios of grounding grids in power systems, specifically including lightning protection assessment, switching overvoltage analysis, and fault location for grounding grids in large substations, transmission lines, and industrial facilities. In practical applications, grounding grids are buried deep underground and are susceptible to soil corrosion and mechanical damage during long-term operation, leading to defects such as conductor breakage and poor contact. By injecting a triangular wave excitation signal into the grounding grid and combining it with response signals collected by high-frequency voltage / current sensors, and using two-dimensional impedance spectrum modeling to analyze the differences in impedance distribution in the horizontal and vertical directions, abnormal areas (such as corrosion points and breakage points) within the grounding grid plane can be accurately identified, providing real-time monitoring and fault early warning support for the safe operation of power systems.

[0170] Figure 6 Flowchart of the high-frequency impedance analysis method for grounding grids provided in this application Figure 2 ,like Figure 6 As shown, in this embodiment... Figures 1 to 5 Based on the examples, the high-frequency impedance analysis method for grounding grids is described in detail. This method includes:

[0171] S601, Triangular wave excitation signal injection.

[0172] (1) Design and generate a triangular wave excitation signal with a specific frequency and amplitude. The frequency range of the triangular wave is set to 1kHz-1MHz, which covers the frequency components of common high-frequency transient currents in power systems. Since the harmonic attenuation of the triangular wave is relatively slow, it can maintain a certain signal strength at a higher frequency range under the same fundamental frequency, which is more conducive to exciting the high-frequency characteristics of the grounding grid. The amplitude is reasonably adjusted according to the scale of the grounding grid and the tolerance of the measuring equipment to ensure that the injected triangular wave signal can effectively excite the grounding grid to exhibit high-frequency characteristics without damaging the measuring equipment and the grounding grid itself.

[0173] (2) The generated triangular wave signal is amplified to a sufficient intensity by a power amplifier, and then the amplified triangular wave excitation signal is safely and stably injected into the grounding grid using a coupling device. The coupling device uses a specially designed high-frequency isolation transformer, which has good high-frequency transmission characteristics and electrical isolation performance, which can avoid electrical interference between the measuring equipment and the grounding grid, while ensuring efficient transmission of the triangular wave signal.

[0174] S602, High-frequency response signal acquisition.

[0175] (1) High-frequency voltage sensors and high-frequency current sensors are arranged at multiple key locations of the grounding grid. The location of the sensors is optimized according to the structural characteristics of the grounding grid and the analysis requirements. For example, sensors are arranged at the edge of the grounding grid, branch nodes, and areas where there may be potential faults, so as to fully capture the high-frequency response signal of the grounding grid under triangular wave excitation.

[0176] (2) The high-frequency voltage sensor adopts a capacitive voltage divider structure, which has wide-band response characteristics and can accurately measure high-frequency voltage signals. The high-frequency current sensor adopts the Rogowski coil principle, which has high sensitivity and linearity for high-frequency current. The sensor converts the collected high-frequency voltage and current signals into electrical signals suitable for processing by the measuring equipment, and transmits them to the data acquisition system through a shielded cable.

[0177] (3) The data acquisition system adopts high-speed sampling technology with a sampling frequency of not less than 10MHz to ensure accurate acquisition of the high-frequency response signal details of the grounding grid under triangular wave excitation. Since the waveform change of the triangular wave is relatively slow, it is easier to accurately capture signal characteristics at the same sampling frequency. At the same time, the data acquisition system has anti-interference function, which effectively suppresses the influence of external high-frequency interference signals on the acquired data through a combination of hardware filtering and software algorithms.

[0178] S603, Calculation of high-frequency impedance characteristics.

[0179] (1) Preprocessing of the high-frequency response signal of the grounding grid includes noise removal, filtering, and signal calibration. Wavelet transform denoising algorithm is used to remove noise components in the acquired signal to the greatest extent while preserving the effective features of the signal. Butterworth low-pass filter is used to filter the signal to remove high-frequency spurious components in the high-frequency response signal, making the signal smoother and facilitating subsequent analysis.

[0180] (2) Use Fourier transform to convert the preprocessed time-domain high-frequency voltage and current signals into frequency-domain signals. According to Ohm's law, calculate the impedance value of the grounding grid at different frequencies in the frequency domain.

[0181] (3) Further analyze the variation of the real part (resistance) and imaginary part (reactance) of the grounding grid impedance with frequency. By plotting the impedance frequency characteristic curve, the changes in the resistance, inductance and capacitance characteristics of the grounding grid in the high-frequency band can be intuitively displayed, thereby gaining a deeper understanding of the high-frequency electrical performance of the grounding grid.

[0182] The high-frequency impedance characteristic analysis results of the grounding grid obtained based on this method can be widely applied to various aspects of power systems, such as lightning protection assessment, switching overvoltage analysis, and grounding grid fault diagnosis. It can provide targeted solutions for the safe and stable operation of power systems, has significant practical application value, and helps improve the overall reliability and safety of power systems.

[0183] In some specific examples, the method includes:

[0184] (1) The triangular wave signal generator and the high-frequency impedance analyzer are connected in a double-ended manner (excitation end and measurement end are on the same line) to inject the excitation signal into the grounding grid and collect the input impedance. .

[0185] (2) Start the triangular wave signal generator, with a base frequency of 10MHz and an amplitude of A 50V even-symmetric triangular wave is used, with a rise time controlled within 20ns to ensure the excitation of the distributed parameter effect of the grounding grid at high frequencies. The signal, after power amplification, is directly injected into the grounding grid input terminal. A high-frequency impedance analyzer scans within the synchronous frequency band, acquiring the amplitude-frequency characteristics of the input impedance. Phase frequency characteristics By subtracting system noise through no-load calibration, a true impedance spectrum curve is generated, providing raw data for subsequent analysis.

[0186] The grounding grid has the same distribution parameters in both the horizontal (x-direction) and vertical (y-direction) directions.

[0187] (3) According to the physical geometric parameters of the grounding grid conductor, including the size of the grounding grid burial depth Soil electrical conductivity Calculate the resistance per unit length based on the distributed parameter model of the grounding electrode. ,inductance ,capacitance and conductivity Complete the parameter configuration of the theoretical model.

[0188] Among them, the complex medium constant of soil is based on The equations were calculated based on local conditions.

[0189] (4) Generate the impedance spectrum according to the following formula and compare it with the measured impedance spectrum for reference analysis:

[0190] ;

[0191] The maximum harmonic order obtained by performing a wideband sweep of 1MHz to 110MHz on a triangular wave with a fundamental frequency of 10MHz is 11.

[0192] The high-frequency impedance analysis method for grounding grids provided in this application significantly improves the accuracy and comprehensiveness of high-frequency characteristic analysis of grounding grids through triangular wave excitation and two-dimensional impedance spectrum analysis. Furthermore, this method can: (1) achieve full coverage of broadband characteristics: triangular wave (such as...) Figure 3 The Fourier series decomposition (shown) contains the fundamental wave and odd harmonics, and the harmonic amplitude increases with frequency according to... The attenuation is regular, and compared to excitation signals such as square waves and trapezoidal waves, the attenuation is smoother, the energy distribution in the mid-to-high frequency band is more balanced, and it can gently and efficiently cover the entire high-frequency transient frequency band of the power system (such as...). This not only avoids signal distortion caused by excessively strong high-order harmonics of square waves and other signals, but also solves the problem of the single excitation frequency of traditional sine waves, and can comprehensively reflect the changes in resistance, inductance and capacitance characteristics of the grounding grid over a wide frequency range.

[0193] (2) Achieve accurate capture of high-frequency parameters: based on the distributed parameter model (considering skin effect and soil complex permittivity). The equations dynamically calculate distributed resistance, inductance, capacitance, and conductance. The harmonic energy distribution characteristics of the triangular wave make it more sensitive to changes in high-frequency parameters. Because the higher harmonic energy of the triangular wave is milder, it will not cause nonlinear distortion of local parameters of the grounding grid due to strong excitation. It can accurately reflect physical phenomena such as the increase in effective conductor resistance and soil dispersion effect at high frequencies, and the error in impedance calculation in the high-frequency band is significantly reduced.

[0194] (3) Enhanced anti-interference capability: The slowly varying characteristics of the triangular wave result in less electromagnetic radiation interference during transmission, giving it an inherent advantage of "source anti-interference". Combined with high-frequency isolation transformer hardware isolation, wavelet transform software denoising, multi-harmonic redundancy verification (such as impedance consistency analysis of different harmonic frequencies) and two-dimensional impedance spectrum spatial comparison ( Methods such as the assumption of consistency of directional parameters can effectively suppress environmental noise and measurement errors.

[0195] (4) Achieve spatial distribution characteristic analysis and precise fault location: Establish a two-dimensional impedance spectrum calculation model ( ), through analysis of the horizontal With longitudinal Differences in impedance distribution (such as spatial variations in amplitude-frequency and phase-frequency characteristics) can identify abnormal distribution parameters within the grounding grid plane caused by corrosion, fracture, etc. The wideband energy balance and high-frequency parameter sensitivity of triangular waves make their impedance characteristics at fault points easier to distinguish from normal areas. Compared to the smooth characteristics under sinusoidal excitation, the fault characteristics of triangular waves show more significant differences, greatly reducing the difficulty of fault point identification (e.g., Figure 4 and Figure 5 As shown in the figure, by combining multi-harmonic feature comparison and spatial deviation analysis, the accuracy of fault location can be significantly improved, providing a precise frequency domain deviation basis for defect location, and solving the problem that the existing one-dimensional model cannot reflect the non-uniformity of planar impedance.

[0196] Figure 7 A schematic diagram of the structure of the high-frequency impedance analysis device for grounding grids provided in this application is shown below. Figure 7 As shown, the grounding grid high-frequency impedance analysis device 70 provided in this embodiment includes:

[0197] The signal generation and injection module 701 is used to acquire a triangular wave excitation signal. The triangular wave excitation signal is an even-symmetric triangular wave signal constructed based on a preset fundamental frequency and amplitude, which is used to inject into the grounding grid.

[0198] The signal acquisition module 702 is used to acquire the response signals of the grounding grid at multiple measurement points based on the triangular wave excitation signal. The response signals include high-frequency voltage signals and high-frequency current signals.

[0199] The data processing and analysis module 703 is used to determine the input impedance spectrum of the grounding grid based on the response signal and the distributed parameter model. The input impedance spectrum is used to evaluate the high-frequency impedance characteristics of the grounding grid.

[0200] In one possible implementation, the signal generation and injection module 701 can also be used to: generate an initial triangular wave excitation signal based on a preset fundamental frequency and amplitude;

[0201] The initial triangular wave excitation signal is amplified by a power amplifier;

[0202] The amplified triangular wave excitation signal is injected into the grounding grid through a preset coupling device.

[0203] In one possible implementation, the signal acquisition module 702 can also be used to: acquire high-frequency voltage signals and high-frequency current signals under triangular wave excitation signals by means of high-frequency voltage sensors and high-frequency current sensors arranged at preset positions in the grounding grid, wherein the preset positions include multiple preset measurement points.

[0204] The response signal includes a high-frequency voltage signal and a high-frequency current signal.

[0205] In one possible implementation, the data processing and analysis module 703 can also be used to: perform a Fourier transform on the response signal to obtain a frequency domain response signal;

[0206] Based on the distributed parameter model, the characteristic impedance and propagation constant of the grounding grid are determined;

[0207] Based on the frequency domain response signal, characteristic impedance, and propagation constant, the input impedance of the grounding grid at the fundamental and harmonic frequencies of the triangular wave excitation signal is determined.

[0208] The input impedance spectrum of the grounding grid is generated based on the input impedance at the fundamental frequency and each harmonic frequency.

[0209] In one possible implementation, the data processing and analysis module 703 can also be used to: generate the theoretical impedance spectrum of the grounding grid based on the two-dimensional impedance spectrum calculation model;

[0210] The input impedance spectrum is compared and analyzed with the theoretical impedance spectrum to obtain the comparison results;

[0211] Based on the comparison results, the performance status and abnormal information of the grounding grid are determined. The abnormal information includes conductor breakage, corrosion or poor contact defects.

[0212] In one possible implementation, the data processing and analysis module 703 can also be used to: combine the input impedances at each frequency into an impedance frequency curve and use the impedance frequency curve as the input impedance spectrum; or, accumulate the input impedances at each frequency to obtain a total impedance spectrum and use the total impedance spectrum as the input impedance spectrum.

[0213] In one possible implementation, the data processing and analysis module 703 can also be used to: sample the response signal based on a preset sampling frequency;

[0214] The sampled response signal is preprocessed, including denoising using wavelet transform and / or filtering using a Butterworth low-pass filter;

[0215] Accordingly, a Fourier transform is performed on the response signal to obtain the frequency domain response signal, including:

[0216] The frequency domain response signal is obtained by performing a Fourier transform on the preprocessed response signal.

[0217] The grounding grid high-frequency impedance analysis device provided in this embodiment can perform the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0218] Figure 8 A schematic diagram of the structure of the electronic device provided in this application. Figure 8 As shown, the electronic device 80 provided in this embodiment includes at least one processor 801 and a memory 802. Optionally, the device 80 further includes a communication component 803. The processor 801, memory 802, and communication component 803 are connected via a bus 804.

[0219] In a specific implementation, at least one processor 801 executes computer execution instructions stored in memory 802, causing at least one processor 801 to perform the above-described method.

[0220] The specific implementation process of processor 801 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0221] 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.

[0222] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0223] 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.

[0224] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0225] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0226] 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.

[0227] 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.

[0228] 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.

[0229] 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.

[0230] 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.

[0231] 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.

[0232] 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.

[0233] It should be understood that the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover but not exclude inclusion. For example, a product or device that includes a series of components is not necessarily limited to those components that are explicitly listed, but may include other components that are not explicitly listed or that are inherent to such product or device.

[0234] As used in this application, the term "module" means any known or subsequently developed hardware, software, firmware, artificial intelligence, fuzzy logic, or combination of hardware and / or software code capable of performing the functions associated with that element.

[0235] 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 high-frequency impedance analysis of grounding grids, characterized in that, include: A triangular wave excitation signal is obtained. The triangular wave excitation signal is an even-symmetric triangular wave signal constructed based on a preset fundamental frequency and amplitude, which is used to inject into the grounding grid. Based on the triangular wave excitation signal, the response signals of the grounding grid at multiple measurement points are obtained, and the response signals include high-frequency voltage signals and high-frequency current signals. Based on the response signal and distributed parameter model, the input impedance spectrum of the grounding grid is determined, and the input impedance spectrum is used to evaluate the high-frequency impedance characteristics of the grounding grid.

2. The method according to claim 1, characterized in that, The acquisition of the triangular wave excitation signal includes: An initial triangular wave excitation signal is generated based on the preset fundamental frequency and amplitude. The initial triangular wave excitation signal is amplified by a power amplifier; The amplified triangular wave excitation signal is injected into the grounding grid through a preset coupling device.

3. The method according to claim 2, characterized in that, The preset coupling device is a high-frequency isolation transformer.

4. The method according to claim 1, characterized in that, The process of acquiring the grounding grid response signals at multiple measurement points based on the triangular wave excitation signal includes: High-frequency voltage and high-frequency current signals under the triangular wave excitation signal are collected by high-frequency voltage and high-frequency current sensors arranged at preset positions on the grounding grid. The preset positions include multiple preset measurement points. The response signal includes the high-frequency voltage signal and the high-frequency current signal.

5. The method according to claim 4, characterized in that, The high-frequency voltage sensor is a capacitive voltage divider type voltage sensor; and / or, the high-frequency current sensor is a current sensor based on the Rogowski coil principle.

6. The method according to any one of claims 1-5, characterized in that, Determining the input impedance spectrum of the grounding grid based on the response signal and the distributed parameter model includes: Perform a Fourier transform on the response signal to obtain the frequency domain response signal; Based on the distributed parameter model, the characteristic impedance and propagation constant of the grounding grid are determined; Based on the frequency domain response signal, the characteristic impedance, and the propagation constant, the input impedance of the grounding grid at the fundamental and harmonic frequencies of the triangular wave excitation signal is determined. The input impedance spectrum of the grounding grid is generated based on the input impedance at the fundamental frequency and each harmonic frequency.

7. The method according to claim 6, characterized in that, The distributed parameter model is a two-dimensional impedance spectrum calculation model, used to analyze the spatial distribution of high-frequency impedance characteristics in the plane of the grounding grid; in the two-dimensional impedance spectrum calculation model, the distributed parameters of the grounding grid are the same in the horizontal and vertical directions.

8. The method according to claim 7, characterized in that, The method further includes: Based on the two-dimensional impedance spectrum calculation model, the theoretical impedance spectrum of the grounding grid is generated; The input impedance spectrum is compared and analyzed with the theoretical impedance spectrum to obtain the comparison results; Based on the comparison results, the performance status and abnormal information of the grounding grid are determined, including conductor breakage, corrosion, or poor contact defects.

9. The method according to claim 6, characterized in that, The step of generating the input impedance spectrum of the grounding grid based on the input impedance at the fundamental frequency and each harmonic frequency includes: The input impedances at each frequency are combined to form an impedance-frequency curve, and the impedance-frequency curve is used as the input impedance spectrum; or, the input impedances at each frequency are accumulated to obtain a total impedance spectrum, and the total impedance spectrum is used as the input impedance spectrum.

10. The method according to claim 6, characterized in that, Before performing a Fourier transform on the response signal to obtain the frequency domain response signal, the method further includes: The response signal is sampled based on a preset sampling frequency; The sampled response signal is preprocessed, including denoising using wavelet transform and / or filtering using a Butterworth low-pass filter. Accordingly, performing a Fourier transform on the response signal to obtain the frequency domain response signal includes: The frequency domain response signal is obtained by performing a Fourier transform on the preprocessed response signal.

11. The method according to any one of claims 1-5, characterized in that, The fundamental frequency range of the triangular wave excitation signal is 1 kHz to 1 MHz.

12. A high-frequency impedance analysis device for grounding grids, characterized in that, include: The signal generation and injection module is used to acquire a triangular wave excitation signal, which is an even-symmetric triangular wave signal constructed based on a preset fundamental frequency and amplitude, and is used to inject into the grounding grid. The signal acquisition module is used to acquire the response signals of the grounding grid at multiple measurement points based on the triangular wave excitation signal, the response signals including high-frequency voltage signals and high-frequency current signals; The data processing and analysis module is used to determine the input impedance spectrum of the grounding grid based on the response signal and the distributed parameter model. The input impedance spectrum is used to evaluate the high-frequency impedance characteristics of the grounding grid.

13. An electronic device, 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 1-11.

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