Grounding grid state evaluation method, device and equipment and readable storage medium

Abstract

A method, apparatus, device, and readable storage medium for assessing the condition of a grounding grid are disclosed. The method includes: measuring the grounding impedance, contact voltage, and step voltage of the grounding grid through a test circuit; correcting the contact voltage and step voltage using a current correction factor; determining the optimal reference point from multiple candidate reference points of the grounding grid based on the on-resistance time series and upstream interference current spectrum of each candidate reference point, and measuring the on-resistance of the optimal reference point; calculating the scores of each of the grounding impedance, contact voltage, step voltage, and on-resistance based on their respective measured values, historical benchmark values, and safety limits, combined with their respective weights; summing the scores to obtain the total condition score of the grounding grid; and determining the safety level of the grounding grid based on the total condition score. This application enables a scientific and accurate assessment of the safety condition of the grounding grid, better ensuring the safe and stable operation of the power system.

Description

Technical Field

[0001] This application relates to the field of power safety technology, and in particular to a grounding grid condition assessment method, apparatus, equipment, and readable storage medium. Background Technology

[0002] The grounding grid is a crucial safeguard for the power system in substations. Its primary function is to provide a path for the dissipation of fault currents. The quality of the grounding grid directly affects the personal safety of personnel within the power plant and the safe operation of all electrical equipment. The grounding grid system is a collective term for multiple buried metal grounding electrodes and the grounding bodies formed by interconnecting these electrodes with conductors to create a mesh structure.

[0003] In hydropower stations and substations, a grounding grid is formed by welding together a dedicated underground grounding electrode and steel bars in the building. All electrical equipment casings and transformer neutral points are connected to this grid. The grounding grid is often distributed in a complex and crisscrossing manner in the underground space according to design requirements and actual layout.

[0004] Accurately assessing the condition of the grounding grid is crucial to ensuring the safe and stable operation of the power system; however, current assessments of the safety condition of the grounding grid are not accurate enough. Summary of the Invention

[0005] This application provides a grounding grid status assessment method, apparatus, device, and readable storage medium, aiming to solve the technical problem that the current assessment of the safety status of grounding grids is not accurate enough.

[0006] In a first aspect, embodiments of this application provide a grounding grid condition assessment method, the grounding grid condition assessment method comprising: The grounding impedance, contact voltage, and step voltage of the grounding grid are measured through the test circuit of the grounding grid. The test circuit includes a current electrode and a voltage electrode. The wiring distance between the current electrode and the voltage electrode and the grounding grid is less than a preset multiple of the diagonal length of the grounding grid. The contact voltage and step voltage are corrected using a current correction factor, and the corrected values ​​of the contact voltage and step voltage are used as new measured values. The current correction factor is determined based on the theoretical return current and the measured return current. The theoretical return current is calculated by a simulation model based on the topology of the grounding grid and the soil resistivity. Among multiple candidate reference points of the grounding grid, the optimal reference point is determined based on the on-resistance time series and upstream interference current spectrum of each candidate reference point, and the on-resistance of the optimal reference point is measured. Based on the measured values, historical benchmark values, and safety limits of grounding impedance, contact voltage, step voltage, and conduction resistance, and their respective weights, scores are calculated for each. The scores are then summed to obtain the total state score of the grounding grid. The safety level of the grounding grid is determined based on the total state score of the grounding grid.

[0007] Optionally, the grounding grid is divided into multiple regions, and determining the optimal reference point among multiple candidate reference points of the grounding grid based on the on-resistance time series and upstream interference current spectrum of each candidate reference point includes: A preset number of reference points are selected from each region as multiple candidate reference points; Obtain the on-resistance time series and upstream interference current spectrum for each candidate reference point; For each candidate reference point, based on the on-resistance time series and the upstream interference current spectrum, the on-resistance fluctuation variance and the peak value of the cross-correlation function with the upstream interference current are calculated. If the difference between the minimum and the second smallest on-resistance fluctuation variance is not less than the preset difference, then the candidate reference point corresponding to the minimum on-resistance fluctuation variance is selected as the optimal reference point. If the difference between the minimum and the second smallest on-resistance fluctuation variances is less than the preset difference, then the candidate reference point corresponding to the smaller peak value of the cross-correlation function between the minimum and the second smallest on-resistance fluctuation variances and the upstream interference current is selected as the optimal reference point.

[0008] Optionally, the grounding grid condition assessment method further includes: If any preset condition is met during the measurement of the on-resistance of the optimal reference point, the process returns to the step of determining the optimal reference point from among multiple candidate reference points in the grounding grid based on the on-resistance time series of each candidate reference point and the upstream interference current spectrum. The preset conditions include: The on-resistance between a preset number of measured points and the optimal reference point exceeds the threshold. The on-resistance of the optimal reference point itself changes by a predetermined proportion compared to the previous measurement. The grounding lead at the optimal reference point is corroded, loose, or broken.

[0009] Optionally, the scores calculated based on the measured values, historical benchmark values, and safety limits of grounding impedance, contact voltage, step voltage, and on-resistance, combined with their respective weights, include: Based on the measured values, historical benchmark values, and safety limits of grounding impedance, touch voltage, step voltage, and on-resistance, and combined with their respective weights, their scores are calculated using Formula 1, which is: ; Among them, Pi K represents the score for one of the following: grounding impedance, contact voltage, step voltage, and on-resistance. i M represents the weight of a certain item. i O represents a measurement value of a certain item. i C represents the historical baseline value of a certain item. i This represents the safety limit for a certain item, where α is the historical decay penalty coefficient and β is the safety margin penalty coefficient, and α+β=1.

[0010] Optionally, the grounding grid condition assessment method further includes: Obtain a score sequence composed of the total status score of the grounding grid across multiple monitoring periods; Using the monitoring period as the independent variable and the total state score of the grounding grid as the dependent variable, a univariate linear regression was performed using the score sequence. The regression slope was calculated using Formula 2, and the calculated regression slope was taken as the rate of change of the total state score of the grounding grid. Formula 2 is as follows: ; Where k is the regression slope, n is the total number of monitoring periods, y is the index, y=1,2,3,...,n,t y This represents the y-th monitoring period. P is the mean value across all monitoring periods. y Let y be the total state score of the y-th grounding grid. This is the average of the total state scores for all grounding grids.

[0011] Optionally, the grounding grid condition assessment method further includes: The early warning level of the grounding grid is determined based on the total state score and rate of change of the grounding grid.

[0012] Optionally, after determining the safety level of the grounding grid based on the total state score of the grounding grid, the following steps are included: The grounding impedance, contact voltage, step voltage, optimal reference point, conduction resistance, total status score, and safety level of the grounding grid are visualized using a three-dimensional model of the grounding grid.

[0013] Secondly, embodiments of this application provide a grounding grid condition assessment device, the grounding grid condition assessment device comprising: The first measurement module is used to measure the grounding impedance, contact voltage and step voltage of the grounding grid through the test circuit of the grounding grid. The test circuit includes a current electrode and a voltage electrode, and the wiring distance between the current electrode and the voltage electrode and the grounding grid is less than a preset multiple of the diagonal length of the grounding grid. The correction module is used to correct the contact voltage and step voltage using a current correction factor, and to use the corrected values ​​of the contact voltage and step voltage as the new measured values. The current correction factor is determined based on the theoretical return current and the measured return current. The theoretical return current is calculated by a simulation model based on the topology of the grounding grid and the soil resistivity. The second measurement module is used to determine the optimal reference point among multiple candidate reference points of the grounding grid based on the on-resistance time series of each candidate reference point and the upstream interference current spectrum, and to measure the on-resistance of the optimal reference point. The evaluation module is used to calculate the scores of each of the grounding impedance, contact voltage, step voltage and on-resistance based on their respective measured values, historical reference values ​​and safety limits, combined with their respective weights. The scores of each are summed to obtain the total state score of the grounding grid, and the safety level of the grounding grid is determined based on the total state score of the grounding grid.

[0014] Thirdly, embodiments of this application provide a grounding grid status assessment device, which includes a processor, a memory, and a grounding grid status assessment program stored in the memory and executable by the processor. When the grounding grid status assessment program is executed by the processor, it implements the steps of the grounding grid status assessment method as described above.

[0015] Fourthly, embodiments of this application provide a readable storage medium storing a grounding grid status assessment program, wherein when the grounding grid status assessment program is executed by a processor, it implements the steps of the grounding grid status assessment method as described above.

[0016] The beneficial effects of the technical solutions provided in this application include: In this embodiment, the grounding impedance, contact voltage, and step voltage of the grounding grid are measured using a test circuit. The test circuit includes current electrodes and voltage electrodes, and the wiring distance between the current electrodes and the grounding grid is less than a preset multiple of the diagonal length of the grounding grid. A current correction factor is used to correct the contact voltage and step voltage, and the corrected values ​​are used as new measured values. The current correction factor is determined based on the theoretical return current and the measured return current. The theoretical return current is calculated by a simulation model based on the topology of the grounding grid and the soil resistivity. Among multiple candidate reference points of the grounding grid, the optimal reference point is determined based on the on-resistance time series and upstream interference current spectrum of each candidate reference point, and the on-resistance of the optimal reference point is measured. Based on the measured values, historical benchmark values, and safety limits of the grounding impedance, contact voltage, step voltage, and on-resistance, and their respective weights, a score is calculated for each. The scores are summed to obtain the total state score of the grounding grid. The safety level of the grounding grid is determined based on the total state score. In this embodiment, the traditional three-level method uses the diagonal length D of the grounding grid as a reference during measurement. The wiring distance between the current electrode and the voltage electrode and the grounding grid is typically 3D-5D. However, considering the large scale and complex terrain of hydropower station grounding grids, making long-distance wiring difficult to implement, this embodiment uses short-distance wiring to shorten the wiring distance between the current electrode and the grounding grid. Due to the shortened wiring distance, the actual return path of the current electrode differs from the ideal infinitely far return point, leading to a systematic deviation between the measured current value and the theoretically calculated current value. To eliminate the impact of this deviation on the measurement results, a simulation model is constructed based on the topology of the grounding grid and the soil resistivity to calculate the theoretical return current. Combined with the actual measured return current, a current correction coefficient is determined to correct the contact voltage and step voltage. Therefore, the short-distance wiring measurement not only conforms to the engineering reality but also ensures the accuracy of the measurement results. To improve the accuracy of measurement parameters, traditional methods for measuring conduction resistance use fixed reference points. However, in large-scale grounding grids of hydropower stations, there are problems such as fluctuations in the performance of the reference point itself, the influence of upstream interference currents, and local corrosion. This embodiment determines the optimal reference point based on the conduction resistance time series and upstream interference current spectrum of each candidate point, thereby improving the measurement accuracy of conduction resistance. By comprehensively considering the deviation of the measured values ​​of various state monitoring parameters of the grounding grid (grounding impedance, contact voltage, step voltage, and conduction resistance) from historical benchmark values ​​(representing time-domain changes) and their closeness to safety limits (representing current risks), and combining their respective weights, the total state score of the grounding grid is calculated, and the corresponding safety level is determined. This enables a scientific and accurate assessment of the safety status of the grounding grid, timely warnings when risks are high, and better protection of the safe and stable operation of the power system. Attached Figure Description

[0017] Figure 1This is a flowchart illustrating an embodiment of the grounding grid condition assessment method of this application; Figure 2 This is another flowchart illustrating an embodiment of the grounding grid condition assessment method of this application; Figure 3 This is a schematic diagram of a three-dimensional model of an embodiment of the grounding grid condition assessment method of this application; Figure 4 This is a functional module diagram of an embodiment of the grounding grid condition assessment device of this application; Figure 5 This is a schematic diagram of the hardware structure of the grounding grid status assessment device involved in the embodiments of this application. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0020] In a first aspect, embodiments of this application provide a method for assessing the condition of a grounding grid.

[0021] In one embodiment, reference is made to Figure 1 , Figure 1 This is a flowchart illustrating an embodiment of the grounding grid condition assessment method of this application, as shown below. Figure 1 As shown, the grounding grid condition assessment methods include: Step S10: Measure the grounding impedance, contact voltage, and step voltage of the grounding grid through the test circuit of the grounding grid. The test circuit includes a current electrode and a voltage electrode, and the wiring distance between the current electrode and the voltage electrode and the grounding grid is less than a preset multiple of the diagonal length of the grounding grid.

[0022] In this embodiment, a variable frequency constant current source can be used as the test excitation power supply, with a frequency of 45Hz or 55Hz to avoid the influence of 50Hz power frequency interference on the measurement signal. The three-electrode method test principle can be adopted, constructing a three-electrode test circuit consisting of a current injection point E, an auxiliary voltage electrode P, and an auxiliary current electrode C. The contact voltage and step voltage measurement systems share the same variable frequency power supply and return current electrode as the grounding impedance test, achieving synchronous acquisition of multiple parameters by switching the measurement circuit. Considering the large scale and complex terrain of hydropower station grounding grids, which makes traditional long-distance wiring difficult to implement, this step sets the wiring distance between the current electrode and voltage electrode and the grounding grid to 1 to 2 times the diagonal length D of the grounding grid, significantly less than the 3D-5D wiring distance required by the conventional three-electrode method. Although short-distance wiring leads to a difference between the actual return path of the current electrode and the ideal infinitely far return point, introducing systematic deviation, this setting greatly reduces the construction difficulty and cost in mountainous or complex terrain. While ensuring the feasibility of the project, it provides basic data for subsequent algorithmic correction of deviations, solving the technical problem that long-distance wiring of large grounding grids cannot be implemented.

[0023] Specifically, in the three-electrode method test, the test current I flows from the grounding device E through the soil medium into the auxiliary current electrode C to form a closed loop. Simultaneously, the potential difference U between the voltage electrode P and the grounding device E is collected, and the grounding impedance measurement value is calculated based on Ohm's law. ,in, This represents the actual grounding resistance of the grounding device. For auxiliary voltage and current inter-electrode mutual resistance, The mutual resistance between the grounding device and the auxiliary voltage electrode. The mutual resistance between the grounding device and the auxiliary current electrode is given by ρ, where ρ is the resistivity and S is the resistance between the grounding device and the auxiliary current electrode. PC To assist the voltage and current inter-electrode radius, S EP S is the radius between the grounding device and the auxiliary voltage electrode. EC Let r be the radius between the grounding device and the auxiliary current electrode, and r be the actual radius of the grounding device.

[0024] Step S20: Correct the contact voltage and step voltage using a current correction factor, and use the corrected values ​​of the contact voltage and step voltage as new measured values. The current correction factor is determined based on the theoretical return current and the measured return current. The theoretical return current is calculated by a simulation model based on the topology of the grounding grid and the soil resistivity.

[0025] In this embodiment, to eliminate measurement deviations caused by short-distance wiring, firstly, based on the measured soil resistivity stratification parameters at the site (including surface thickness and resistivity of each layer) and the actual burial location of the current electrodes, a full-scale electromagnetic field simulation calculation model including the grounding grid, voltage electrodes, current electrodes, and soil stratification structure is established in a numerical simulation platform to obtain the theoretical return current Ic. Secondly, the measured return current Im is recorded synchronously in the test circuit. Finally, a current correction coefficient α = Ic / Im is constructed, which comprehensively reflects the combined influence of factors such as the mutual impedance between the current electrodes and the grounding grid and soil stratification characteristics on the return current under short-distance wiring conditions. The measured contact voltage Utm and step voltage Usm are multiplied by the correction coefficient α to obtain the corrected contact voltage Utc and step voltage Usc. By using a high-precision simulation model to restore the current distribution under ideal conditions, the degree of deviation is quantified by the ratio of the measured value to the theoretical value. This approach ensures that short-distance wiring measurements are consistent with actual engineering conditions, while also guaranteeing the accuracy of measurement parameters through coefficient correction, thus eliminating potential difference measurement distortion caused by shortened wiring distances.

[0026] Step S30: Among multiple candidate reference points of the grounding grid, determine the optimal reference point based on the on-resistance time series and upstream interference current spectrum of each candidate reference point, and measure the on-resistance of the optimal reference point.

[0027] In this embodiment, the grounding grid can be divided into multiple regions (such as dam area, powerhouse area, outgoing line area, etc.), and a preset number of reference points are selected from each region as candidate reference points. For example, the on-resistance time series and upstream interference current spectrum of each candidate reference point are collected on a quarterly basis. For each candidate reference point, the on-resistance fluctuation variance and the peak value of the cross-correlation function with the upstream interference current are calculated. If the difference between the smallest and second smallest on-resistance fluctuation variances is not less than a preset difference, the point with the smallest fluctuation variance is selected; if the difference is less than the preset difference, the point with the smaller cross-correlation function peak value is selected. Here, the on-resistance fluctuation variance reflects the stability of the reference point itself, while the peak value of the cross-correlation function reflects the degree to which the reference point is affected by the upstream interference current. By selecting the optimal reference point through dual indicators, the one-sidedness of selecting a single indicator can be avoided, thereby solving the problem that the measurement benchmark fails due to corrosion, performance fluctuation, or interference of traditional fixed reference points. Dynamically optimizing the reference point improves the reliability and accuracy of on-resistance measurement.

[0028] Step S40: Based on the measured values, historical benchmark values, and safety limits of grounding impedance, contact voltage, step voltage, and conduction resistance, and their respective weights, calculate their respective scores, sum the scores to obtain the total state score of the grounding grid, and determine the safety level of the grounding grid based on the total state score of the grounding grid.

[0029] In this embodiment, the calculation of scores comprehensively considers the deviation of the measured value from the historical benchmark value (representing time-domain changes) and the degree of proximity to the safety limit (representing current risk). Finally, the scores of each item are summed to obtain the total state score. Based on the total state score, the safety level of the grounding grid is divided into five risk levels, which are identified using different colors (such as green, blue, yellow, orange, and red) when displaying the 3D model. Compared with the traditional static threshold assessment, which only focuses on whether the current standard is exceeded, this method introduces the comparison of historical baselines and safety limits, which can reflect the performance degradation trend and safety status. It can scientifically and accurately quantify the safety status of the grounding grid, overcome the limitations of traditional static threshold assessment, and provide timely warnings when the risk is high, thus better ensuring the safe and stable operation of the power system.

[0030] Specifically, based on the total status score, the safety level of the grounding grid is divided into five risk levels. The scores and specific descriptions for each level are as follows: Level I (85~100 points): Indicates that the grounding grid is in good condition, with almost no reduction in performance indicators. In this case, the surface of the corresponding 3D visualization model is overlaid with a green color mark, and the transparency is 30%. Level II (70~85 points): Indicates that the grounding grid is currently in good operating condition. Some grounding conductors may have slight corrosion, and the electrical performance of the grounding grid is slightly reduced. The possibility of failure is low, and the maintenance cycle can be appropriately extended. In this case, the surface of the corresponding 3D visualization model is overlaid with a blue color mark, and the transparency is 40%. Level III (60~70 points): Indicates that the grounding grid is in safe operating condition. Some key electrical performance indicators may have increased significantly, but are still within safety limits. The grounding conductors may have moderate corrosion. Regular inspections of the grounding grid should be ensured. Level IV (40-60 points): This indicates a high safety risk in the grounding grid's operation. Due to prolonged operation or harsh operating environments, conductor corrosion is severe, and some key electrical performance indicators have significantly declined. Key electrical parameters should be retested promptly to further confirm the safety status. If a high safety risk is indeed found, rectification and repair should be carried out. In this case, the 3D visualization model shows an orange color mark overlaid on the surface of this area, with a transparency of 60%. Level V (<40 points): This indicates a very high safety risk in the grounding grid's operation. Key electrical performance of the grounding grid has significantly decreased, and the grounding conductor may have experienced severe corrosion. The possibility of a safety accident is high when the grounding current is high. Rectification and repair of the grounding grid should be carried out. In this case, the 3D visualization model shows a red color mark overlaid on the surface of this area, with a transparency of 70%.

[0031] In this embodiment, the grounding impedance, contact voltage, and step voltage of the grounding grid are measured using the three-electrode method and short-distance wiring. This solves the technical problem of long-distance wiring for large grounding grids being impractical. Coefficient correction ensures the accuracy of measurement parameters and eliminates potential difference measurement distortion caused by shortened wiring distance. Dual-index selection of the optimal reference point for conducting resistance measurement avoids the bias of single-index selection and solves the problem of measurement benchmark failure due to corrosion, performance fluctuations, or interference of traditional fixed reference points. Dynamically optimizing reference points improves the reliability and accuracy of conducting resistance measurement. Compared to traditional static threshold assessments that only focus on current exceedances, this method introduces a comparison between historical baselines and safety limits, reflecting performance degradation trends and safety status. This enables a scientific and accurate quantitative assessment of the grounding grid's safety status, overcoming the limitations of traditional static threshold assessments and providing timely warnings when risks are high, thus better ensuring the safe and stable operation of the power system.

[0032] Further, in one embodiment, the grounding grid is divided into multiple regions, and determining the optimal reference point among multiple candidate reference points of the grounding grid based on the on-resistance time series and upstream interference current spectrum of each candidate reference point includes: A preset number of reference points are selected from each region as multiple candidate reference points; Obtain the on-resistance time series and upstream interference current spectrum for each candidate reference point; For each candidate reference point, based on the on-resistance time series and the upstream interference current spectrum, the on-resistance fluctuation variance and the peak value of the cross-correlation function with the upstream interference current are calculated. If the difference between the minimum and the second smallest on-resistance fluctuation variance is not less than the preset difference, then the candidate reference point corresponding to the minimum on-resistance fluctuation variance is selected as the optimal reference point. If the difference between the minimum and the second smallest on-resistance fluctuation variances is less than the preset difference, then the candidate reference point corresponding to the smaller peak value of the cross-correlation function between the minimum and the second smallest on-resistance fluctuation variances and the upstream interference current is selected as the optimal reference point.

[0033] In this embodiment, a different frequency power supply can be used to measure the DC resistance R between the candidate reference point lead and the designated reference point on the main network using the four-wire method. ref,i (t), continuously collected for 7 days, with 3 time points each day (peak load, valley load, and flat load), to form the on-resistance time series R of this candidate reference point for this quarter. i ={r1,r2,...,r n A broadband current transformer is installed at the main grounding down conductor of the outgoing line yard / switching station to continuously monitor the interference current injected into the grounding grid from the upstream system. The fundamental frequency and harmonic amplitudes at each time point are recorded synchronously to form the upstream interference current spectrum sequence I.intf (t). Based on the above collected data, two quantitative evaluation indicators are calculated for each candidate reference point: on-resistance fluctuation variance. , where R ij This represents the on-resistance measured at the i-th candidate reference point in the j-th measurement. This represents the average on-resistance during this cycle. The peak value of the cross-correlation function with the upstream interference current. , where R i (t) represents the on-resistance value of the i-th candidate reference point at time t, I intf (t-τ) represents the amplitude of the upstream interference current at time t-τ. This represents the average upstream interference current. When the stability (variance) of two candidate points is very close (the difference is less than a preset difference, such as 0.5 mΩ²), it indicates that it is difficult to distinguish between them based solely on their own stability. In this case, an anti-interference index (cross-correlation peak value) is introduced. This is because, under conditions of comparable stability, the point less affected by external interference better reflects the true state of the grounding grid. Through a two-stage screening mechanism, the reference point is selected in its optimal state of stability and minimal external interference, thereby improving the confidence of the monitoring data.

[0034] Furthermore, in one embodiment, the grounding grid status assessment method further includes: If any preset condition is met during the measurement of the on-resistance of the optimal reference point, the process returns to the step of determining the optimal reference point from among multiple candidate reference points in the grounding grid based on the on-resistance time series of each candidate reference point and the upstream interference current spectrum. The preset conditions include: The on-resistance between a preset number of measured points and the optimal reference point exceeds the threshold. The on-resistance of the optimal reference point itself changes by a predetermined proportion compared to the previous measurement. The grounding lead at the optimal reference point is corroded, loose, or broken.

[0035] In this embodiment, an anomaly feedback mechanism is established. When multiple consecutive measured points (e.g., more than 5) show poor continuity with the optimal reference point, or when the resistance of the reference point changes abruptly compared to the previous measurement (e.g., exceeding 20%), or when damage is discovered during physical inspection, the system forcibly triggers a reselection of the optimal reference point. These phenomena indicate that the current reference point may have failed or suffered severe corrosion, making it unsuitable as the optimal reference point for measuring conduction resistance. This prevents data distortion throughout the evaluation cycle due to reference point failure, ensuring the robustness of the monitoring system. Furthermore, the switching events of the optimal reference point can be recorded in the 3D visualization model, enabling traceable management.

[0036] Furthermore, in one embodiment, the calculation of scores based on the measured values, historical benchmark values, and safety limits of grounding impedance, contact voltage, step voltage, and on-resistance, combined with their respective weights, includes: Based on the measured values, historical benchmark values, and safety limits of grounding impedance, touch voltage, step voltage, and on-resistance, and combined with their respective weights, their scores are calculated using Formula 1, which is: ; Among them, P i K represents the score for one of the following: grounding impedance, contact voltage, step voltage, and on-resistance. i M represents the weight of a certain item. i O represents a measurement value of a certain item. i C represents the historical baseline value of a certain item. i This represents the safety limit for a certain item, where α is the historical decay penalty coefficient and β is the safety margin penalty coefficient, and α+β=1.

[0037] In this embodiment, the formula combines the deviations (time-domain variations) of the measured values ​​of grounding impedance, contact voltage, step voltage, and on-resistance relative to historical benchmark values ​​with their proximity to safety limits (current risk), overcoming the limitations of traditional static threshold assessments. Grounding impedance, contact voltage, step voltage, and on-resistance are all cost-related parameters, calculated using the upper part of the formula. This formula provides a calculation method for effect-related parameters (such as insulation strength and safety margin), allowing for the addition of more assessment parameters to the grounding grid status score assessment as needed. α and β can be set based on engineering experience. For example, for older grounding grids with longer operating years, the weight of α can be appropriately increased to focus more on the degree of performance degradation relative to the benchmark; for newly built grounding grids, the weight of β can be increased to focus more on whether the current performance is close to the safety limit. Since the risk assessment focus differs for grounding grids at different lifecycles, by giving the assessment system flexibility, the assessment results are made more closely aligned with the actual operating lifecycle characteristics of the power grid, avoiding the error of a "one-size-fits-all" approach.

[0038] Specifically, the weights K of each item iThe analytic hierarchy process (AHP) can be used to determine the following steps: First, establish a pairwise comparison matrix A for each parameter, where the eigenvectors represent the weights of each parameter. Matrix A contains four parameters: contact voltage, step voltage, grounding impedance, and conduction resistance. Second, compare and judge the merits of the evaluation schemes. For each of the four parameters, set up pairwise comparison matrices for the four schemes: B1, B2, B3, and B4, representing the comparison matrices for contact voltage, step voltage, grounding impedance, and conduction resistance, respectively. The significance of matrix B is that its eigenvectors represent the merits of the four schemes for a given parameter. Third, calculate the weight coefficients of each parameter, i.e., calculate the values ​​of the unknowns in matrix A. Let the unknown elements in matrix A be x and y, and pre-assign values ​​to the remaining elements according to the scaling method. Let the unknown elements in matrices B1, B2, B3, and B4 be a, b, c, and d, respectively, and pre-assign values ​​to the remaining elements according to the scaling method. First, set initial values: x=1, y=1, a=1, b=1, c=1, d=1, to obtain matrices A and B. Then, using the following formula, calculate the eigenvectors of A and B1, B2, B3, and B4: Let the eigenvector of A be U', and the eigenvectors of B1, B2, B3, and B4 be ω(B1), ω(B2), ω(B3), and ω(B4); calculate the score according to the following formula: Since Scheme I represents the original data of the hydropower station, i.e., the best data indicators measured under the same conditions, its final score, P1, is 100 points. Schemes II, III, IV, and V represent individual data exceeding the standard for a 110kV hydropower station, respectively, so their scores are no greater than 60 points, which is taken as 60 here. Following this theory, we modify the elements in matrices A and B1, B2, B3, and B4 in sequence, ultimately making P1≈100, P2≈60, P3≈60, and P4≈60. After calculating x and y in matrix A, we can obtain the eigenvectors of matrix A, i.e., the weights of each parameter.

[0039] Furthermore, in one embodiment, the grounding grid status assessment method further includes: Obtain a score sequence composed of the total status score of the grounding grid across multiple monitoring periods; Using the monitoring period as the independent variable and the total state score of the grounding grid as the dependent variable, a univariate linear regression was performed using the score sequence. The regression slope was calculated using Formula 2, and the calculated regression slope was taken as the rate of change of the total state score of the grounding grid. Formula 2 is as follows: ; Where k is the regression slope, n is the total number of monitoring periods, y is the index, y=1,2,3,...,n,t y This represents the y-th monitoring period. is the mean value for all monitoring periods, P y is the total status score of the y-th grounding grid, is the mean value of the total status scores of all grounding grids.

[0040] In this embodiment, if only looking at the current score, it may cover up the trend of rapid deterioration. Therefore, introducing a univariate linear regression in the time dimension can predict the future state trajectory. Extending the evaluation dimension from the "current state section" to the "future state trajectory" realizes a fundamental transformation from passive alarm to active early warning, and can identify potential risks in advance. Among them, the regression slope k quantitatively describes the average decline rate of the grounding grid health state over time. The larger the absolute value of k, the faster the deterioration speed.

[0041] Furthermore, in one embodiment, the grounding grid status evaluation method further includes: Determining the early warning level of the grounding grid based on the total status score and the change rate of the grounding grid.

[0042] In this embodiment, according to the current total status score P and the change rate k of the grounding grid, multiple early warning levels are divided to compensate for the lag of single-score evaluation, provide an immediate intervention signal for rapid deterioration, and guide the maintenance personnel to reasonably arrange the maintenance plan (such as increasing the monitoring frequency or conducting special inspections). Specifically, the early warning levels can be divided as follows: (1) When k≥-0.2 or P≥85, it means that the grounding grid status is stable or in the I-level interval, and maintenance can be carried out according to the original plan. At this time, there is no early warning, and the early warning level shown in the 3D model is 0. (2) When -0.5≤k<-0.2 and 70<P<85, it means that the deterioration trend of the grounding grid status begins to appear, but it has not yet affected the safety level. The monitoring period should be increased, and this is a level-1 early warning. The early warning level shown in the 3D model is 1. (3) When k<-0.5 and P≥70, it means that the deterioration speed of the grounding grid status is significantly accelerating. Currently, it still belongs to level II / III, but it may drop below level III within 1-2 years, triggering the retest process. This is a level-2 early warning, and the early warning level shown in the 3D model is 2. (4) When k<-1.0 and P≥70, it means that the deterioration speed of the grounding grid status is extremely fast. Even if the current score is acceptable, it is actually in a high-risk critical state. Immediately arrange special inspections and demonstration of the rectification plan. This is a level-3 early warning, and the early warning level shown in the 3D model is 3. (5) When P<70, regardless of the value of k, the early warning level is set to 4, indicating that the grounding grid in this area has entered level III or below, and the corresponding maintenance requirements at this level should be strictly implemented immediately, and the monitoring period should be shortened by half.

[0043] Furthermore, in one embodiment, referring to Figure 2 , Figure 2 is another process schematic diagram of an embodiment of the grounding grid status evaluation method of this application, as Figure 2As shown, after determining the safety level of the grounding grid based on the total state score of the grounding grid, the following steps are included: In step S50, the grounding impedance, contact voltage, step voltage, optimal reference point, conduction resistance, total status score, and safety level of the grounding grid are visualized using a three-dimensional model of the grounding grid.

[0044] In this embodiment, the underground grounding grid has a complex spatial distribution, making it difficult for two-dimensional drawings to intuitively represent the correspondence between spatial location and state. (Refer to...) Figure 3 , Figure 3 This is a schematic diagram of a three-dimensional model of an embodiment of the grounding grid condition assessment method of this application, as shown below. Figure 3 As shown, a full-scene 3D grounding grid model can be constructed using a multi-software collaborative modeling technology combining AutoCAD, 3ds Max, and Unity. The system utilizes KKS encoding to achieve automatic data-model association. Figure 3 Based on the shown 3D model, the comprehensive score is superimposed onto the surface of the corresponding area model using a continuously gradient pseudo-color layer (five color gamuts: green / blue / yellow / orange / red), with transparency dynamically adjusted according to the risk level. A 3D floating information board is automatically generated at the geometric center of the warning area, displaying the current score, the change curve over the past three years, the estimated remaining time before the first entry into a less safe state, and a suggested retest window. By spatializing and visualizing abstract data, the cognitive load on maintenance personnel is reduced, fault location and decision-making efficiency is improved, and a digital decision-making environment for the grounding grid status that is perceptible, traceable, and predictable is formed.

[0045] Secondly, embodiments of this application also provide a grounding grid condition assessment device.

[0046] In one embodiment, reference is made to Figure 4 , Figure 4 This is a functional module diagram of an embodiment of the grounding grid condition assessment device of this application, as shown below. Figure 4 As shown, the grounding grid condition assessment device includes: The first measurement module 10 is used to measure the grounding impedance, contact voltage and step voltage of the grounding grid through the test circuit of the grounding grid. The test circuit includes a current electrode and a voltage electrode, and the wiring distance between the current electrode and the voltage electrode and the grounding grid is less than a preset multiple of the diagonal length of the grounding grid. The correction module 20 is used to correct the contact voltage and step voltage using a current correction coefficient, and to use the corrected values ​​of the contact voltage and step voltage as new measured values. The current correction coefficient is determined based on the theoretical return current and the measured return current. The theoretical return current is calculated by a simulation model based on the topology of the grounding grid and the soil resistivity. The second measurement module 30 is used to determine the optimal reference point among multiple candidate reference points of the grounding grid based on the on-resistance time series of each candidate reference point and the upstream interference current spectrum, and to measure the on-resistance of the optimal reference point. The evaluation module 40 is used to calculate the scores of each of the grounding impedance, contact voltage, step voltage and conduction resistance based on their respective measured values, historical reference values ​​and safety limits, combined with their respective weights. The scores of each are summed to obtain the total state score of the grounding grid, and the safety level of the grounding grid is determined based on the total state score of the grounding grid.

[0047] Furthermore, in one embodiment, the grounding grid is divided into multiple regions, and the determination of the optimal reference point among multiple candidate reference points of the grounding grid, based on the on-resistance time series and upstream interference current spectrum of each candidate reference point, is used for: A preset number of reference points are selected from each region as multiple candidate reference points; Obtain the on-resistance time series and upstream interference current spectrum for each candidate reference point; For each candidate reference point, based on the on-resistance time series and the upstream interference current spectrum, the on-resistance fluctuation variance and the peak value of the cross-correlation function with the upstream interference current are calculated. If the difference between the minimum and the second smallest on-resistance fluctuation variance is not less than the preset difference, then the candidate reference point corresponding to the minimum on-resistance fluctuation variance is selected as the optimal reference point. If the difference between the minimum and the second smallest on-resistance fluctuation variances is less than the preset difference, then the candidate reference point corresponding to the smaller peak value of the cross-correlation function between the minimum and the second smallest on-resistance fluctuation variances and the upstream interference current is selected as the optimal reference point.

[0048] Furthermore, in one embodiment, the grounding grid condition assessment device further includes a reselection module, used for: If any preset condition is met during the measurement of the on-resistance of the optimal reference point, the process returns to the step of determining the optimal reference point from among multiple candidate reference points in the grounding grid based on the on-resistance time series of each candidate reference point and the upstream interference current spectrum. The preset conditions include: The on-resistance between a preset number of measured points and the optimal reference point exceeds the threshold. The on-resistance of the optimal reference point itself changes by a predetermined proportion compared to the previous measurement. The grounding lead at the optimal reference point is corroded, loose, or broken.

[0049] Furthermore, in one embodiment, the scores calculated based on the measured values, historical reference values, and safety limits of grounding impedance, contact voltage, step voltage, and on-resistance, combined with their respective weights, are used for: Based on the measured values, historical benchmark values, and safety limits of grounding impedance, touch voltage, step voltage, and on-resistance, and combined with their respective weights, their scores are calculated using Formula 1, which is: ; Among them, P i K represents the score for one of the following: grounding impedance, contact voltage, step voltage, and on-resistance. i M represents the weight of a certain item. i O represents a measurement value of a certain item. i C represents the historical baseline value of a certain item. i This represents the safety limit for a certain item, where α is the historical decay penalty coefficient and β is the safety margin penalty coefficient, and α+β=1.

[0050] Furthermore, in one embodiment, the grounding grid condition assessment device further includes a calculation module for: Obtain a score sequence composed of the total status score of the grounding grid across multiple monitoring periods; Using the monitoring period as the independent variable and the total state score of the grounding grid as the dependent variable, a univariate linear regression was performed using the score sequence. The regression slope was calculated using Formula 2, and the calculated regression slope was taken as the rate of change of the total state score of the grounding grid. Formula 2 is as follows: ; Where k is the regression slope, n is the total number of monitoring periods, y is the index, y=1,2,3,...,n,t y This represents the y-th monitoring period. P is the mean value across all monitoring periods. y Let y be the total state score of the y-th grounding grid. This is the average of the total state scores for all grounding grids.

[0051] Furthermore, in one embodiment, the grounding grid status assessment device further includes an early warning module, used for: The early warning level of the grounding grid is determined based on the total state score and rate of change of the grounding grid.

[0052] Furthermore, in one embodiment, the grounding grid status assessment device further includes a display module, used for: The grounding impedance, contact voltage, step voltage, optimal reference point, conduction resistance, total status score, and safety level of the grounding grid are visualized using a three-dimensional model of the grounding grid.

[0053] The functions of each module in the above-mentioned grounding grid condition assessment device correspond to the steps in the above-mentioned grounding grid condition assessment method embodiment, and their functions and implementation processes will not be described in detail here.

[0054] Thirdly, embodiments of this application provide a grounding grid condition assessment device.

[0055] Reference Figure 5 , Figure 5 This is a schematic diagram of the hardware structure of the grounding grid condition assessment device involved in the embodiments of this application. In this embodiment, the grounding grid condition assessment device may include a processor, a memory, a communication interface, and a communication bus.

[0056] The communication bus can be of any type and is used to interconnect the processor, memory, and communication interface.

[0057] The communication interface includes input / output (I / O) interfaces, physical interfaces, and logical interfaces used for interconnecting internal components of the grounding grid condition assessment equipment, as well as interfaces used for interconnecting the grounding grid condition assessment equipment with other devices (such as other computing devices or user equipment). Physical interfaces can be Ethernet interfaces, fiber optic interfaces, ATM interfaces, etc.; user equipment can be displays, keyboards, etc.

[0058] Memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), etc.

[0059] The processor can be a general-purpose processor, which can call the grounding grid status assessment program stored in the memory and execute the grounding grid status assessment method provided in the embodiments of this application. For example, the general-purpose processor can be a central processing unit (CPU). The method executed when the grounding grid status assessment program is called can be referred to in the various embodiments of the grounding grid status assessment method of this application, and will not be repeated here.

[0060] Those skilled in the art will understand that Figure 5 The hardware structure shown does not constitute a limitation of this application and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0061] Fourthly, embodiments of this application also provide a readable storage medium.

[0062] The present application has a grounding grid condition assessment program stored on a readable storage medium, wherein when the grounding grid condition assessment program is executed by a processor, it implements the steps of the grounding grid condition assessment method as described above.

[0063] The method implemented when the grounding grid condition assessment procedure is executed can be referred to in various embodiments of the grounding grid condition assessment method of this application, and will not be repeated here.

[0064] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0065] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequence, nor do they limit "first," "second," and "third" to different types.

[0066] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0067] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0068] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0069] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0070] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for assessing the condition of a grounding grid, characterized in that, The grounding grid condition assessment method includes: The grounding impedance, contact voltage, and step voltage of the grounding grid are measured through the test circuit of the grounding grid. The test circuit includes a current electrode and a voltage electrode. The wiring distance between the current electrode and the voltage electrode and the grounding grid is less than a preset multiple of the diagonal length of the grounding grid. The contact voltage and step voltage are corrected using a current correction factor, and the corrected values ​​of the contact voltage and step voltage are used as new measured values. The current correction factor is determined based on the theoretical return current and the measured return current. The theoretical return current is calculated by a simulation model based on the topology of the grounding grid and the soil resistivity. Among multiple candidate reference points of the grounding grid, the optimal reference point is determined based on the on-resistance time series and upstream interference current spectrum of each candidate reference point, and the on-resistance of the optimal reference point is measured. Based on the measured values, historical benchmark values, and safety limits of grounding impedance, contact voltage, step voltage, and conduction resistance, and their respective weights, scores are calculated for each. The scores are then summed to obtain the total state score of the grounding grid. The safety level of the grounding grid is determined based on the total state score of the grounding grid.

2. The grounding grid condition assessment method as described in claim 1, characterized in that, The grounding grid is divided into multiple regions. Determining the optimal reference point from among multiple candidate reference points in the grounding grid, based on the on-resistance time series and upstream interference current spectrum of each candidate reference point, includes: A preset number of reference points are selected from each region as multiple candidate reference points; Obtain the on-resistance time series and upstream interference current spectrum for each candidate reference point; For each candidate reference point, based on the on-resistance time series and the upstream interference current spectrum, the on-resistance fluctuation variance and the peak value of the cross-correlation function with the upstream interference current are calculated. If the difference between the minimum and the second smallest on-resistance fluctuation variance is not less than the preset difference, then the candidate reference point corresponding to the minimum on-resistance fluctuation variance is selected as the optimal reference point. If the difference between the minimum and the second smallest on-resistance fluctuation variances is less than the preset difference, then the candidate reference point corresponding to the smaller peak value of the cross-correlation function between the minimum and the second smallest on-resistance fluctuation variances and the upstream interference current is selected as the optimal reference point.

3. The grounding grid condition assessment method as described in claim 1, characterized in that, The grounding grid condition assessment method also includes: If any preset condition is met during the measurement of the on-resistance of the optimal reference point, the process returns to the step of determining the optimal reference point from among multiple candidate reference points in the grounding grid based on the on-resistance time series of each candidate reference point and the upstream interference current spectrum. The preset conditions include: The on-resistance between a preset number of measured points and the optimal reference point exceeds the threshold. The on-resistance of the optimal reference point itself changes by a predetermined proportion compared to the previous measurement. The grounding lead at the optimal reference point is corroded, loose, or broken.

4. The grounding grid condition assessment method as described in claim 1, characterized in that, The scores are calculated based on the measured values, historical benchmark values, and safety limits of grounding impedance, contact voltage, step voltage, and on-resistance, combined with their respective weights, including: Based on the measured values, historical benchmark values, and safety limits of grounding impedance, touch voltage, step voltage, and on-resistance, and combined with their respective weights, their scores are calculated using Formula 1, which is: ； Among them, P i K represents the score for one of the following: grounding impedance, contact voltage, step voltage, and on-resistance. i M represents the weight of a certain item. i O represents a measurement value of a certain item. i C represents the historical baseline value of a certain item. i This represents the safety limit for a certain item, where α is the historical decay penalty coefficient and β is the safety margin penalty coefficient, and α+β=1.

5. The grounding grid condition assessment method as described in claim 1, characterized in that, The grounding grid condition assessment method also includes: Obtain a score sequence composed of the total status score of the grounding grid across multiple monitoring periods; Using the monitoring period as the independent variable and the total state score of the grounding grid as the dependent variable, a univariate linear regression was performed using the score sequence. The regression slope was calculated using Formula 2, and the calculated regression slope was taken as the rate of change of the total state score of the grounding grid. Formula 2 is as follows: ； Where k is the regression slope, n is the total number of monitoring periods, y is the index, y=1,2,3,...,n,t y This represents the y-th monitoring period. P is the mean value across all monitoring periods. y Let y be the total state score of the y-th grounding grid. This is the average of the total state scores for all grounding grids.

6. The grounding grid condition assessment method as described in claim 5, characterized in that, The grounding grid condition assessment method also includes: The early warning level of the grounding grid is determined based on the total state score and rate of change of the grounding grid.

7. The grounding grid condition assessment method as described in claim 1, characterized in that, After determining the safety level of the grounding grid based on the total state score of the grounding grid, the following is included: The grounding impedance, contact voltage, step voltage, optimal reference point, conduction resistance, total status score, and safety level of the grounding grid are visualized using a three-dimensional model of the grounding grid.

8. A grounding grid condition assessment device, characterized in that, The grounding grid condition assessment device includes: The first measurement module is used to measure the grounding impedance, contact voltage and step voltage of the grounding grid through the test circuit of the grounding grid. The test circuit includes a current electrode and a voltage electrode, and the wiring distance between the current electrode and the voltage electrode and the grounding grid is less than a preset multiple of the diagonal length of the grounding grid. The correction module is used to correct the contact voltage and step voltage using a current correction factor, and to use the corrected values ​​of the contact voltage and step voltage as the new measured values. The current correction factor is determined based on the theoretical return current and the measured return current. The theoretical return current is calculated by a simulation model based on the topology of the grounding grid and the soil resistivity. The second measurement module is used to determine the optimal reference point among multiple candidate reference points of the grounding grid based on the on-resistance time series of each candidate reference point and the upstream interference current spectrum, and to measure the on-resistance of the optimal reference point. The evaluation module is used to calculate the scores of each of the grounding impedance, contact voltage, step voltage and on-resistance based on their respective measured values, historical reference values ​​and safety limits, combined with their respective weights. The scores of each are summed to obtain the total state score of the grounding grid, and the safety level of the grounding grid is determined based on the total state score of the grounding grid.

9. A grounding grid condition assessment device, characterized in that, The grounding grid condition assessment device includes a processor, a memory, and a grounding grid condition assessment program stored in the memory and executable by the processor, wherein when the grounding grid condition assessment program is executed by the processor, it implements the steps of the grounding grid condition assessment method as described in any one of claims 1 to 7.

10. A readable storage medium, characterized in that, The readable storage medium stores a grounding grid status assessment program, wherein when the grounding grid status assessment program is executed by a processor, it implements the steps of the grounding grid status assessment method as described in any one of claims 1 to 7.

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