Pole tower grounding resistance data acquisition device and lightning stroke resistance analysis method

Abstract

The invention discloses a tower grounding resistance data acquisition device and an anti-lightning analysis method, and relates to the technical field of tower grounding resistance measurement. The device for carrying out tower grounding resistance data acquisition by using the unmanned aerial vehicle comprises a grounding resistance sensor which is positioned below a tower and is connected with a ground line body, a mainframe box which is in wired connection with the grounding resistance sensor, and a data receiving device which is in data transmission connection with the mainframe box and is mounted on the unmanned aerial vehicle, the ground resistance sensor collects the ground resistance of the ground line body and transmits the ground resistance data to the mainframe box. When the unmanned aerial vehicle carries out polling between towers, the host box transmits grounding resistance data to the data receiving device through the communication module in the host box, so that a background manager obtains the grounding resistance data of each tower through the data receiving device, the working efficiency of grounding resistance detection is improved, and the large-scale detection requirement is met.

Description

Technical Field

[0001] The invention relates to the technical field of pole tower grounding resistance measurement, and in particular to a pole tower grounding resistance data acquisition device and a lightning strike resistance analysis method. Background Art

[0002] In today's power sector, with the continuous expansion and complexity of power networks, higher requirements are placed on the stable operation and safety of power equipment. As an important supporting structure for power transmission, the accurate measurement of the grounding resistance of the tower is crucial to ensure the safe and stable operation of the power system. With the rapid development of science and technology, the application of intelligent and automated detection technology in the power industry has received more and more attention.

[0003] In traditional tower grounding resistance measurement, it is usually necessary to manually climb to the tower, remove the grounding lead, and then use professional measuring instruments for measurement. This method is not only labor-intensive but also inefficient. The measurement process is easily disturbed by environmental factors such as weather and terrain, which affects the accuracy and reliability of the measurement results. In addition, due to the large number of towers in the power system and their wide distribution, the traditional manual measurement method is difficult to meet the needs of large-scale and rapid detection.

[0004] Importance of ground resistance monitoring:

[0005] All kinds of buildings and equipment, especially power system terminals, must be reliably grounded with lightning protection ground wires. The quality of ground resistance is related to the safety of the power system. In order to improve the lightning protection level of lightning protection ground wires in engineering, the ground resistance of the ground wire must be reduced. However, due to factors such as damage, corrosion, and drought, the ground resistance may change significantly. Real-time monitoring of ground resistance is of great significance to ensure that the static electricity of the equipment casing and the strong current of the lightning rod are safely discharged into the earth when lightning strikes.

[0006] Limitations of existing measurement methods:

[0007] ① The megohmmeter method is based on the principle of measuring pure resistance and is not suitable for measuring the grounding resistance of a large-area ground grid.

[0008] ②Although the 0.618 method and the isosceles triangle method belong to voltage and current methods, their measurement methods are inconvenient, and currently grounding resistance is mostly measured manually, which is inefficient and difficult to guarantee accuracy.

[0009] Existing technical solutions:

[0010] The measurement of the grounding resistance of the tower mainly relies on manual operation. The staff needs to climb to the tower, manually remove the grounding down conductor, and then use professional measuring instruments for measurement. This method has many obvious defects: first, the operation of manually climbing the tower is not only labor-intensive, but also dangerous; second, the process of removing the grounding down conductor is cumbersome and complicated, and it takes a lot of time and energy; third, the measurement process is easily affected by weather conditions (such as strong winds, thunderstorms, etc.), terrain conditions (such as hills, rivers, etc.) and the surrounding electromagnetic environment, thus affecting the accuracy and reliability of the measurement results; in addition, due to the large number of towers in the power system and their wide distribution, the use of this method of manual measurement of each tower is extremely inefficient, and it is difficult to complete large-scale detection tasks in a short time. Summary of the invention

[0011] In order to solve the above problems, the present invention provides a device for collecting tower grounding resistance data using a drone, which does not require manual climbing and removal of grounding down leads, reduces operation risks and labor intensity, can avoid interference from environmental factors, and improves measurement accuracy and reliability. Data is collected by rapid flight of drones, which greatly improves work efficiency and meets large-scale detection requirements.

[0012] The technical solution adopted by the present invention is:

[0013] A device for collecting tower grounding resistance data using a drone, the device comprising a grounding resistance sensor located below the tower and connected to a ground line body, a mainframe connected to the grounding resistance sensor by wire, and a data receiving device connected to the mainframe for data transmission and installed on the drone;

[0014] The grounding resistance sensor collects the grounding resistance of the ground line body and transmits the grounding resistance data to the main box; when the drone performs inspection between poles and towers, the main box transmits the grounding resistance data to the data receiving device through its internal communication module.

[0015] Further, the ground resistance sensor adopts a coupling sensor, which includes a rated current generator and a current electrode connected to the ground line body, and a voltmeter and a voltage electrode connected to the ground line body;

[0016] The coupling sensor provides a stable excitation current through a rated current generator, introduces a measurable current into the ground loop under test, and the current electrode measures the current flowing through the ground loop; the voltmeter measures the voltage caused by the excitation pulse in the ground loop, that is, the pulse potential E, and the voltage electrode is in contact with the ground loop; the coupling sensor calculates the resistance of the measured loop through the formula R=E / I.

[0017] Furthermore, the host case includes a waterproof host case, a power module located in the case body, a host control board connected to the power module, a host switch, a host charging interface, a host display screen, and a signal transmitting module connected to the host control board; wherein the host display screen, the host switch and the host charging interface are exposed to the outside of the waterproof host case, and the host control board is connected to the grounding resistance sensor via a connecting wire passing through the case.

[0018] Furthermore, a photovoltaic power generation panel is installed on the top of the waterproof host chassis, and the photovoltaic power generation panel is connected to the power module through the host control board.

[0019] A method for performing lightning strike protection analysis through tower grounding resistance, based on the above-mentioned device for collecting tower grounding resistance data using a drone, comprises the following steps:

[0020] Step 1, using a drone to collect the grounding resistance of the ground line body using a grounding resistance sensor of a tower grounding resistance data collection device, and transmitting the grounding resistance data to a main box;

[0021] Step 2, when the drone conducts inspection between pole towers, the main box of the pole tower grounding resistance data acquisition device of the drone transmits the grounding resistance data to the data receiving device installed on the drone, so that the background management system obtains the grounding resistance data of each pole tower;

[0022] Step 3, the background management system performs data preprocessing on the ground resistance data of each tower;

[0023] Step 4, the background management system extracts features from the pre-processed ground resistance data of each tower;

[0024] Step 5: The background management system analyzes and evaluates the characteristics of the ground resistance data of each tower based on the lightning protection model;

[0025] Step 6: The backend management system provides reports and optimization suggestions based on the analysis and evaluation of the ground resistance data of each tower, including: key events, feature extraction data, model analysis results and lightning resistance scores.

[0026] Further, in step 3, data preprocessing is performed on the ground resistance data of each tower, including the following steps:

[0027] Step 3.1, clean the data:

[0028] Statistical methods are used to detect outliers. The calculation formula is as follows:

[0029]

[0030] Where Z is an outlier; X is a single measurement; μ is the mean of the data; σ is the standard deviation of the data;

[0031] By setting the threshold, outliers can be identified and removed;

[0032] The missing values ​​are processed by interpolation method. The linear interpolation calculation formula is as follows:

[0033]

[0034] Where y is the interpolation result at x; (x 1 ,y 1 ) and (x 2 ,y 2 ) are known data points;

[0035] Step 3.2, data segmentation:

[0036] By segmenting the time and location data, the data interval before and after the lightning strike event is identified; the time segmentation extracts the data before and after the lightning strike event by setting a time window T; the location segmentation is to identify the different locations or regions of the data source through the change of location in the geographic location data, and locate the impact of the lightning strike;

[0037] Step 3.3, smoothing and filtering:

[0038] Apply filtering algorithms to reduce high-frequency interference signals and improve the signal-to-noise ratio of data; before filtering, the data needs to be smoothed by a sliding average method;

[0039] The sliding average method eliminates short-term fluctuations by averaging the data. A window size n is set and the mean of the data in the window is calculated using the following formula:

[0040]

[0041] In the formula, y i is the smoothed data; x j is the original data; n is the size of the sliding window; i represents the position of the center of the current window in the original data; j represents the specific position in the original data;

[0042] Select the filter order N and cutoff frequency f c , the transfer function of the filter is as follows;

[0043]

[0044] Where H(s) is the filter transfer function; s is the complex frequency variable; ω c =2πf c , is the angular frequency of the cut-off frequency; N is the order of the filter;

[0045] The filter is used to process the original data, eliminate high-frequency components and retain low-frequency signals.

[0046] Further, in step 4, the feature extraction of the pre-processed ground resistance data of each tower includes the following steps:

[0047] Step 4.1, time domain features:

[0048] Extracting time domain features includes: extracting the average value, variance, peak value, and pulse index to describe the resistance change before and after the lightning strike;

[0049] The calculation formula for extracting the average value is as follows:

[0050]

[0051] In the formula, Mean is the average value; N is the total number of data samples; x i is the sample value of the signal;

[0052] The variance is extracted by the following formula, which measures the volatility of the signal;

[0053]

[0054] In the formula, Variance is the variance; N is the total number of data samples; x i is the sample value of the signal; Mean is the average value;

[0055] The peak value is extracted by the following formula to represent the instantaneous response during lightning strike;

[0056] PeakValue=max(x i )

[0057] Where PeakValue is the peak value; x i is the sample value of the signal;

[0058] The pulse index is extracted by the following formula to measure the strength of the pulse signal;

[0059]

[0060] Where, ImpulseFactor is the pulse index; PeakValue is the peak value; Mean is the average value;

[0061] Step 4.2, frequency domain features:

[0062] The signal is converted to the frequency domain through fast Fourier transform (FFT) to analyze the frequency characteristics of lightning current and voltage. The frequency characteristics of lightning current and voltage include: frequency distribution and bandwidth;

[0063] The calculation formula of fast Fourier transform is as follows:

[0064]

[0065] Where X(f) is the frequency component; x n is the nth sample value of the time domain signal; f is the frequency; N is the total number of samples;

[0066] Frequency distribution: The frequency spectrum of the signal is obtained through FFT, so as to analyze the distribution of the main frequency components;

[0067] Bandwidth describes the frequency range of a signal and is calculated as follows:

[0068] Bandwidth = fhigh-flow

[0069] Where, Bandwidth is the bandwidth; fhigh is the cutoff frequency of the high-frequency component in the spectrum; flow is the cutoff frequency of the low-frequency component in the spectrum;

[0070] Step 4.3, time-frequency domain features:

[0071] Short-time Fourier transform (STFT) is used to obtain the joint information of time and frequency and capture the instantaneous characteristics of lightning strikes.

[0072] The calculation formula of short-time Fourier transform STFT is as follows:

[0073]

[0074] Where X(t,f) is the signal component at time t and frequency f; x(τ) is the original signal; ω(τ-t) is the window function; e is the base of the natural logarithm, which is approximately equal to 2.71828; j is the imaginary unit; 2π is a constant; f is the frequency; τ is a variable with respect to time;

[0075] Step 4.4, impulse response characteristics:

[0076] Analyze the transient voltage and current response caused by lightning pulse to evaluate the impact of lightning on the grounding system;

[0077] The transient response is used to describe the voltage and current changes of the system under pulse input. The calculation formula is as follows:

[0078] R(t)=V(t) / I(t)

[0079] Where R(t) is the equivalent resistance at time t; V(t) and I(t) are the voltage and current at time t respectively;

[0080] The duration of the pulse from the beginning to the end is measured as the pulse width; the maximum voltage or current value of the pulse is the pulse peak value, which is used to quantify the impact intensity of the lightning strike.

[0081] Further, in step 5, the anti-lightning model is a statistical model, and the statistical model uses multivariate regression analysis to analyze the relationship between the grounding resistance and environmental factors before and after the lightning strike to infer the response mode of the grounding resistance to the lightning strike;

[0082] Select the influencing factors of ground resistance as independent variables and the ground resistance value as dependent variable, construct a multivariate regression equation, fit the relationship between ground resistance and environmental factors under lightning events, and thus construct a multivariate regression model;

[0083] The multivariate regression equation is as follows:

[0084] R=β 0 +β 1 X 1 +β 2 X 2 +...+β n X n +ε

[0085] Where R is the grounding resistance; X 1 , X 2 , …X n For different influencing factors; β 0 is the bias term, β 1 , β 2 , …β n is the regression coefficient; ε is the error term;

[0086] Use the least squares method to solve the regression coefficient β value, minimize the error sum of squares, estimate the influence of various factors on ground resistance, and achieve model fitting and parameter estimation;

[0087] Use goodness of fit R 2 Test the explanatory power of the model, use significance test to analyze whether each factor has a significant impact on ground resistance, and realize model verification and inference;

[0088] Input environmental factor values, predict the change of grounding resistance under lightning strike, evaluate the lightning resistance of the grounding system under different environments, and realize the predictive application of the model.

[0089] Further, in step 5, the characteristics of the ground resistance data of each tower are analyzed and evaluated, including: calculating the recovery time, stabilization time, and resistance change after recovery of the ground resistance after the lightning strike event, so as to evaluate the lightning resistance recovery capability of the grounding system;

[0090] The recovery time is the time interval from the occurrence of the lightning strike to the recovery of the ground resistance to a steady state, and the calculation formula is as follows:

[0091] T recovery =t recovered -t event

[0092] Where, T recovery is the recovery time; t recovered is the time point when the resistance returns to the steady state; t event is the time point when the lightning strike occurred;

[0093] The stabilization time is the time interval during which the resistance reaches and remains at a stable value during the recovery time. The calculation formula is as follows:

[0094] T stable =t stable end -t stable start

[0095] Where, T stable is the stabilization time; t stable end The time it takes for the resistance to enter the stable range; t stable start To keep the resistance at the end of the stable range;

[0096] The resistance change is the peak change of ground resistance caused by the lightning strike event, and the calculation formula is as follows:

[0097] ΔR=R peak -R baseline

[0098] Where ΔR is the resistance change; R peak is the instantaneous resistance peak value of lightning strike; R baseline is the steady-state resistance value before the lightning strike.

[0099] Beneficial effects:

[0100] The device for collecting tower grounding resistance data using a drone has the following beneficial effects:

[0101] The device for collecting tower grounding resistance data using a drone collects the grounding resistance of the ground line body through a grounding resistance sensor, and transmits the grounding resistance data to a main box. When the drone conducts inspections between towers, the main box transmits the grounding resistance data to a data receiving device through its internal communication module, so that the back-end management personnel can obtain the grounding resistance data of each tower through the data receiving device, thereby improving the work efficiency of grounding resistance detection and meeting large-scale detection requirements.

[0102] The device for collecting tower grounding resistance data by using drones uses drones for data collection, which can quickly cover widely distributed areas such as transmission line towers, greatly shortening the data collection time; compared with the traditional manual measurement method, it is no longer necessary to measure each tower manually, which improves the overall measurement efficiency. The grounding resistance sensor can accurately measure the grounding loop resistance, further improving the accuracy of the measurement results; the main box and the data receiving device use LORA wireless communication to ensure the accuracy of data transmission and avoid errors in the data transmission process.

[0103] The method for analyzing lightning strike resistance through tower grounding resistance has the following beneficial effects:

[0104] This method of analyzing lightning strike resistance through tower grounding resistance uses the data acquisition device carried by the drone to realize real-time monitoring of tower grounding resistance, ensure timely detection of abnormal conditions of the grounding system, and thus enhance the effectiveness of lightning protection. The coupling sensor is used to collect grounding resistance data, which can directly measure and calculate current and voltage, provide an accurate and reliable data basis for subsequent analysis, and improve the credibility of the analysis results. The background management system preprocesses and extracts features for data, which can efficiently analyze large amounts of data, reduce manual intervention, and improve work efficiency. By analyzing the grounding resistance data through the lightning strike resistance model, the performance of the grounding system under the risk of lightning strikes can be evaluated, potential problems can be identified in advance, and the pertinence and effectiveness of the maintenance strategy can be improved. The reports and optimization suggestions generated by the system can provide scientific decision-making support for relevant managers, thereby promoting the continuous optimization and safety management of the tower grounding system.

[0105] The method of conducting lightning protection analysis through tower grounding resistance can significantly improve the safety and reliability of power infrastructure and reduce losses caused by lightning strikes. BRIEF DESCRIPTION OF THE DRAWINGS

[0106] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0107] Figure 1 The overall layout diagram of the device for collecting tower grounding resistance data using a drone according to the present invention;

[0108] Figure 2 It is a schematic diagram of the connection between the coupling sensor and the ground line body of the present invention;

[0109] Figure 3 and Figure 4 It is a structural schematic diagram of the mainframe box of the present invention;

[0110] Figure 5 A flow chart of a method for performing lightning protection analysis through tower grounding resistance according to the present invention;

[0111] In the figure: 1. Pole tower; 2. Ground resistance sensor; 3. Host box; 4. Drone; 5. Data receiving device; 6. Waterproof host box; 7. Power module; 8. Host control board; 9. Host switch; 10. Host charging port; 11. Signal transmission module; 12. Host display screen; 13. Photovoltaic power generation panel. DETAILED DESCRIPTION

[0112] The following will be combined with the drawings of the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0113] Example 1

[0114] The measurement of the grounding resistance of the tower mainly relies on manual operation. The staff needs to climb to the tower, manually remove the grounding lead, and then use professional measuring instruments to measure. This embodiment provides a device for collecting tower grounding resistance data using a drone; Figure 1 As shown, the device for collecting tower grounding resistance data using a drone includes a grounding resistance sensor 2 located below the tower 1 and connected to the ground line body, a main box 3 connected to the grounding resistance sensor 2 by wire, and a data receiving device 5 connected to the main box 3 for data transmission and installed on a drone 4.

[0115] The ground resistance sensor 2 is a commercially available coupling sensor, such as Figure 2 As shown, the coupling sensor includes a rated current generator and a current electrode connected to the ground line body, and a voltmeter and a voltage electrode connected to the ground line body. The rated current generator inside the coupling sensor applies an excitation pulse signal to the ground loop. The function of this signal is to provide a known current source for the ground loop, so that a current flows in the ground line. Under the influence of the excitation signal, the ground loop will generate a current I. At this time, the voltmeter and voltage electrode of the coupling sensor are connected to the ground loop to measure the potential E (voltage) generated by the current flow in the loop. This voltage reflects the voltage drop when the current passes through the ground loop. According to Ohm's law, the ground resistance R can be calculated using the formula R=E / I, where E is the measured voltage and I is the current passing through the ground loop. Through the given excitation signal and the corresponding voltage and current measurement, the coupling sensor can accurately calculate the value of the ground resistance.

[0116] Since the coupling sensor itself does not have the data transmission function, a main box 3 is provided in this embodiment for the transmission of ground loop resistance data. The main box 3 can be installed by hanging it on the tower at the bottom of each tower 1 through a hanger, or by installing and fixing it on the ground near the tower 1 through a prefabricated concrete mounting seat. Figure 3 and Figure 4 As shown, the host box 3 in this embodiment includes a waterproof host box 6, a power module 7 located in the box body, a host control board 8 connected to the power module 7, a host switch 9 connected to the host control board 8, a host charging interface 10, and a signal transmitting module 11. Among them, the waterproof host box 6 is a metal box structure, the power module 7 uses a commercially available 6VDC-12VDC power supply; the host control board 8 uses an Arduino Mega 2560 host controller, and the host controller is equipped with a data storage function; the signal transmitting module 11 uses a commercially available Semtech SX1276 LoRa long-distance wireless module; the host switch 9 and the host charging interface 10 are exposed outside the waterproof host box 6, and the host control board 8 is connected to the ground resistance sensor 2 through a connecting line passing through the box.

[0117] Since the power grid currently uses drones 4 to inspect transmission lines, drones 4 are used as carriers and data receiving devices 5 are installed. The data receiving devices 5 are mainly data storage devices and Semtech SX1276 LoRa long-distance wireless modules. When drones 4 perform inspection tasks near pole towers 1, data receiving devices 5 and host boxes 3 establish a data transmission channel through the LoRa long-distance wireless module, so that the ground loop resistance data stored in the host control board 8 is transmitted to the data storage device of the data receiving device 5 for storage. When drones 4 complete the inspection of transmission lines along the pipeline area, they receive the ground loop resistance data of all pole towers 1. After drones 4 land, backstage managers connect to the data receiving device 5 through computers to export data and obtain all ground loop resistance data.

[0118] Further, as a preferred technical solution of this embodiment, considering that the on-site personnel can know the ground loop resistance data of the corresponding position tower 1 in real time, such as Figure 2 As shown, in this embodiment, a host display screen 12 is also installed on the box body of the waterproof host chassis 6. The host display screen 12 is connected to the host control board 8, and the grounding loop resistance data collected by the grounding resistance sensor 2 is displayed in real time through the host display screen 12.

[0119] In addition, as the preferred technical solution of this embodiment, a photovoltaic panel 13 is also installed on the top outside the waterproof host chassis 6. The photovoltaic panel 13 is connected to the power module 7 through the host control board 8. The photovoltaic panel 13 uses commercially available finished equipment to convert solar energy into electrical energy to charge the power module 7, so as to ensure the long-term and stable operation of the host chassis 3.

[0120] To sum up, the device for collecting tower grounding resistance data using a drone collects the grounding resistance of the ground line body through the grounding resistance sensor 2, and transmits the grounding resistance data to the main box 3. When the drone 4 inspects the tower 1, the main box 3 transmits the grounding resistance data to the data receiving device 5 through its internal communication module, so that the background management personnel can obtain the grounding resistance data of each tower through the data receiving device 5, thereby improving the work efficiency of grounding resistance detection and meeting large-scale detection requirements.

[0121] Example 2

[0122] Based on Example 1, this example proposes a method for performing lightning protection analysis through tower grounding resistance, such as Figure 5 As shown, the method specifically comprises the following steps:

[0123] Step 1: Use a drone to collect the grounding resistance of the ground line body using a grounding resistance sensor of a tower grounding resistance data collection device, and transmit the grounding resistance data to a main box.

[0124] Step 2: When the drone conducts inspection between pole towers, the main box of the pole tower grounding resistance data acquisition device of the drone transmits the grounding resistance data to the data receiving device installed on the drone, so that the background management system obtains the grounding resistance data of each pole tower.

[0125] Step 3, the background management system performs data preprocessing on the ground resistance data of each tower;

[0126] The data preprocessing of the ground resistance data of each tower includes the following steps:

[0127] Step 3.1, clean the data:

[0128] Use statistical methods, such as Z-score, to detect outliers. The calculation formula is as follows:

[0129]

[0130] Where Z is an outlier; X is a single measurement; μ is the mean of the data; σ is the standard deviation of the data;

[0131] By setting a threshold, such as |Z|>3, outliers are identified and removed;

[0132] The missing values ​​are processed by interpolation method. The linear interpolation calculation formula is as follows:

[0133]

[0134] Where y is the interpolation result at x; (x 1 ,y 1 ) and (x 2 ,y 2 ) are known data points;

[0135] Step 3.2, data segmentation:

[0136] By segmenting the time and location data, the data interval before and after the lightning strike event is identified; time segmentation extracts the data before and after the lightning strike event by setting a time window T, for example, a period of 30 seconds before and after the lightning strike; location segmentation is to identify different locations or regions of the data source through changes in location in the geographic location data, and locate the impact of the lightning strike;

[0137] Step 3.3, smoothing and filtering:

[0138] Apply filtering algorithms to reduce high-frequency interference signals and improve the signal-to-noise ratio of data; before filtering, the data needs to be smoothed by a sliding average method;

[0139] The sliding average method eliminates short-term fluctuations by averaging the data. A window size n is set and the mean of the data in the window is calculated using the following formula:

[0140]

[0141] In the formula, y i is the smoothed data; x j is the original data; n is the size of the sliding window; i represents the position of the center of the current window in the original data; j represents the specific position in the original data.

[0142] Select the filter order N and cutoff frequency f c , the transfer function of the filter is as follows;

[0143]

[0144] Where H(s) is the filter transfer function; s is the complex frequency variable; ω c =2πf c , is the angular frequency of the cut-off frequency; N is the order of the filter;

[0145] The filter is used to process the original data, eliminate high-frequency components and retain low-frequency signals.

[0146] Step 4, the background management system extracts features from the pre-processed ground resistance data of each tower;

[0147] Extracting the features of the pre-processed ground resistance data of each tower includes the following steps:

[0148] Step 4.1, time domain features:

[0149] Extracting time domain features includes: extracting the average value, variance, peak value, and pulse index to describe the resistance change before and after the lightning strike;

[0150] The calculation formula for extracting the average value is as follows:

[0151]

[0152] In the formula, Mean is the average value; N is the total number of data samples; x i is the sample value of the signal;

[0153] The variance is extracted by the following formula, which measures the volatility of the signal;

[0154]

[0155] In the formula, Variance is the variance; N is the total number of data samples; x i is the sample value of the signal; Mean is the average value;

[0156] The peak value is extracted by the following formula to represent the instantaneous response during lightning strike;

[0157] PeakValue=max(x i )

[0158] Where PeakValue is the peak value; x i is the sample value of the signal;

[0159] The pulse index is extracted by the following formula to measure the strength of the pulse signal;

[0160]

[0161] Where, ImpulseFactor is the pulse index; PeakValue is the peak value; Mean is the average value;

[0162] Step 4.2, frequency domain features:

[0163] The signal is converted to the frequency domain through fast Fourier transform (FFT) to analyze the frequency characteristics of lightning current and voltage. The frequency characteristics of lightning current and voltage include: frequency distribution and bandwidth;

[0164] The calculation formula of fast Fourier transform is as follows:

[0165]

[0166] Where X(f) is the frequency component; x n is the nth sample value of the time domain signal; f is the frequency; N is the total number of samples;

[0167] Frequency distribution: The frequency spectrum of the signal is obtained through FFT, so as to analyze the distribution of the main frequency components;

[0168] Bandwidth describes the frequency range of a signal and is calculated as follows:

[0169] Bandwidth = fhigh-flow

[0170] Where, Bandwidth is the bandwidth; fhigh is the cutoff frequency of the high-frequency component in the spectrum; flow is the cutoff frequency of the low-frequency component in the spectrum;

[0171] Step 4.3, time-frequency domain features:

[0172] Short-time Fourier transform (STFT) is used to obtain the joint information of time and frequency and capture the instantaneous characteristics of lightning strikes.

[0173] The calculation formula of short-time Fourier transform STFT is as follows:

[0174]

[0175] Where X(t,f) is the signal component at time t and frequency f; x(τ) is the original signal; ω(τ-t) is the window function; e is the base of the natural logarithm, which is approximately equal to 2.71828; j represents the imaginary unit; 2π is a constant; f is the frequency; and τ is a variable with respect to time.

[0176] Step 4.4, impulse response characteristics:

[0177] Analyze the transient voltage and current response caused by lightning pulse to evaluate the impact of lightning on the grounding system;

[0178] The transient response is used to describe the voltage and current changes of the system under pulse input. The calculation formula is as follows:

[0179] R(t)=V(t) / I(t)

[0180] Where R(t) is the equivalent resistance at time t; V(t) and I(t) are the voltage and current at time t respectively;

[0181] The duration of the pulse from the beginning to the end is measured as the pulse width; the maximum voltage or current value of the pulse is the pulse peak value, which is used to quantify the impact intensity of the lightning strike.

[0182] Step 5: The background management system analyzes and evaluates the characteristics of the ground resistance data of each tower based on the lightning protection model;

[0183] Among them, the lightning strike resistance model is a statistical model. The statistical model uses multivariate regression analysis to analyze the relationship between ground resistance and environmental factors before and after lightning strike to infer the response mode of ground resistance to lightning strike;

[0184] Select the influencing factors of ground resistance, such as humidity, temperature, soil resistivity, etc., as independent variables, and the ground resistance value as the dependent variable, construct a multivariate regression equation, fit the relationship between ground resistance and environmental factors under lightning events, and thus construct a multivariate regression model;

[0185] The multivariate regression equation is as follows:

[0186] R=β 0 +β 1 X 1 +β 2 X 2 +...+β n X n +ε

[0187] Where R is the grounding resistance; X 1 , X 2 , …X n For different influencing factors, such as humidity, soil resistivity; β 0 is the bias term, β 1 , β 2 , …β n is the regression coefficient; ε is the error term;

[0188] Use the least squares method to solve the regression coefficient β value, minimize the error sum of squares, estimate the influence of various factors on ground resistance, and achieve model fitting and parameter estimation;

[0189] Use goodness of fit R 2 Test the explanatory power of the model and use significance tests, such as t-tests, to analyze whether each factor has a significant impact on grounding resistance, so as to achieve model verification and inference;

[0190] Input environmental factor values, predict the change of grounding resistance under lightning strike, evaluate the lightning resistance of the grounding system under different environments, and realize the predictive application of the model.

[0191] Analyze and evaluate the characteristics of the ground resistance data of each tower, including: calculate the recovery time, stabilization time, and resistance change after recovery of the ground resistance after a lightning strike, so as to evaluate the lightning resistance recovery capability of the grounding system;

[0192] The recovery time is the time interval from the occurrence of the lightning strike to the recovery of the ground resistance to a steady state, and the calculation formula is as follows:

[0193] T recovery =t recovered -t event

[0194] Where, T recovery is the recovery time; t recovered is the time point when the resistance returns to the steady state; t event is the time point when the lightning strike occurred;

[0195] The stabilization time is the time interval during which the resistance reaches and remains at a stable value during the recovery time. The calculation formula is as follows:

[0196] T stable =t stable end -t stable start

[0197] Where, T stable is the stabilization time; t stable end The time it takes for the resistance to enter the stable range; t stable start To keep the resistance at the end of the stable range;

[0198] The resistance change is the peak change of ground resistance caused by the lightning strike event, and the calculation formula is as follows:

[0199] R=R peak -R baseline

[0200] Where ΔR is the resistance change; R peak is the instantaneous resistance peak value of lightning strike; R baseline is the steady-state resistance value before the lightning strike.

[0201] Step 6: The backend management system provides reports and optimization suggestions based on the analysis and evaluation of the ground resistance data of each tower, including: key events, feature extraction data, model analysis results and lightning resistance scores.

[0202] Based on the output data of the lightning protection model (such as maximum voltage, recovery time, rate of change, etc.), the lightning protection capability of the grounding system is quantitatively scored.

[0203] Rating dimensions:

[0204] Maximum voltage / current impact (Vmax, Imax): reflects the system's transient response capability to lightning strikes.

[0205] Recovery time (T recovery ): Reflects the speed at which the system recovers from a lightning strike.

[0206] Stabilization time (T stable ): reflects the system stability.

[0207] Resistance change rate (ΔR / R baseline ): Measures the impact of a lightning strike on ground resistance.

[0208] Scoring criteria:

[0209] Maximum voltage / current impact points S 1 : If the impact value is below a certain threshold, a high score is obtained, otherwise it is reduced proportionally.

[0210] Recovery time score S 2 : The shorter the recovery time, the higher the score.

[0211] Stable time fraction S 3 : The shorter the stabilization time, the higher the score.

[0212] Electropositive change rate fraction S 4 : The lower the rate of change, the higher the score.

[0213] Lightning resistance level classification:

[0214] According to the total score S, the lightning resistance of the grounding system is divided into different levels, such as "excellent" (80-100 points), "good (60-80 points), general" (40-60 points) and "poor" (0-20 points).

[0215] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A device for collecting tower grounding resistance data using an unmanned aerial vehicle, characterized in that: The device for collecting tower grounding resistance data using a drone comprises a grounding resistance sensor located below the tower and connected to a ground line body, a mainframe connected to the grounding resistance sensor by wire, and a data receiving device connected to the mainframe for data transmission and installed on the drone; The ground resistance sensor collects the ground resistance of the ground line body and transmits the ground resistance data to the main box; When the drone performs inspection between pole towers, the main box transmits the grounding resistance data to the data receiving device through the internal communication module.

2. The device for collecting tower grounding resistance data using an unmanned aerial vehicle according to claim 1, characterized in that: The ground resistance sensor adopts a coupling sensor, which includes a rated current generator and a current electrode connected to the ground line body, and a voltmeter and a voltage electrode connected to the ground line body; The coupling sensor provides a stable excitation current through a rated current generator, introduces a measurable current into the ground loop under test, and the current electrode measures the current flowing through the ground loop; the voltmeter measures the voltage caused by the excitation pulse in the ground loop, that is, the pulse potential E, and the voltage electrode is in contact with the ground loop; the coupling sensor calculates the resistance of the measured loop through the formula R=E / I.

3. The device for collecting tower grounding resistance data using an unmanned aerial vehicle according to claim 1, characterized in that: The host case includes a waterproof host case, a power module located in the case body, a host control board connected to the power module, a host switch, a host charging interface, a host display screen, and a signal transmitting module connected to the host control board; wherein the host display screen, the host switch, and the host charging interface are exposed to the outside of the waterproof host case, and the host control board is connected to the grounding resistance sensor via a connecting wire passing through the case.

4. The device for collecting tower grounding resistance data using an unmanned aerial vehicle according to claim 3, characterized in that: A photovoltaic power generation panel is also installed on the top of the waterproof host chassis, and the photovoltaic power generation panel is connected to the power module through the host control board.

5. A method for lightning protection analysis through tower grounding resistance, the method is based on the device for collecting tower grounding resistance data using a drone as described in any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1, using a drone to collect the grounding resistance of the ground line body using a grounding resistance sensor of a tower grounding resistance data collection device, and transmitting the grounding resistance data to a main box; Step 2, when the drone conducts inspection between pole towers, the main box of the pole tower grounding resistance data acquisition device of the drone transmits the grounding resistance data to the data receiving device installed on the drone, so that the background management system obtains the grounding resistance data of each pole tower; Step 3, the background management system performs data preprocessing on the ground resistance data of each tower; Step 4, the background management system extracts features from the pre-processed ground resistance data of each tower; Step 5: The background management system analyzes and evaluates the characteristics of the ground resistance data of each tower based on the lightning protection model; Step 6: The backend management system provides reports and optimization suggestions based on the analysis and evaluation of the ground resistance data of each tower, including: key events, feature extraction data, model analysis results and lightning resistance scores.

6. The method for performing lightning protection analysis through tower grounding resistance according to claim 5, characterized in that: In step 3, data preprocessing is performed on the ground resistance data of each tower, including the following steps: Step 3.1, clean the data: Statistical methods are used to detect outliers. The calculation formula is as follows: Where Z is an outlier; X is a single measurement; μ is the mean of the data; σ is the standard deviation of the data; By setting the threshold, outliers can be identified and removed; The missing values ​​are processed by interpolation method. The linear interpolation calculation formula is as follows: Where y is the interpolation result at x; (x1, y1) and (x2, y2) are known data points; Step 3.2, data segmentation: By segmenting the time and location data, the data interval before and after the lightning strike event is identified; the time segmentation extracts the data before and after the lightning strike event by setting a time window T; the location segmentation is to identify the different locations or regions of the data source through the change of location in the geographic location data, and locate the impact of the lightning strike; Step 3.3, smoothing and filtering: Apply filtering algorithms to reduce high-frequency interference signals and improve the signal-to-noise ratio of data; before filtering, the data needs to be smoothed by a sliding average method; The sliding average method eliminates short-term fluctuations by averaging the data. A window size n is set and the mean of the data in the window is calculated using the following formula: In the formula, y i is the smoothed data; x j is the original data; n is the size of the sliding window; i represents the position of the center of the current window in the original data; j represents the specific position in the original data; Select the filter order N and cutoff frequency f c , the transfer function of the filter is as follows; Where H(s) is the filter transfer function; s is the complex frequency variable; ω c =2πf c , is the angular frequency of the cut-off frequency; N is the order of the filter; The filter is used to process the original data, eliminate high-frequency components and retain low-frequency signals.

7. The method for performing lightning protection analysis through tower grounding resistance according to claim 5, characterized in that: In step 4, the features of the pre-processed ground resistance data of each tower are extracted, including the following steps: Step 4.1, time domain features: Extracting time domain features includes: extracting the average value, variance, peak value, and pulse index to describe the resistance change before and after the lightning strike; The calculation formula for extracting the average value is as follows: In the formula, Mean is the average value; N is the total number of data samples; x i is the sample value of the signal; The variance is extracted by the following formula, which measures the volatility of the signal; In the formula, Variance is the variance; N is the total number of data samples; x i is the sample value of the signal; Mean is the average value; The peak value is extracted by the following formula to represent the instantaneous response during lightning strike; PeakValue=max(x i ) Where PeakValue is the peak value; x i is the sample value of the signal; The pulse index is extracted by the following formula to measure the strength of the pulse signal; Where, ImpulseFactor is the pulse index; PeakValue is the peak value; Mean is the average value; Step 4.2, frequency domain features: The signal is converted to the frequency domain through fast Fourier transform (FFT) to analyze the frequency characteristics of lightning current and voltage. The frequency characteristics of lightning current and voltage include: frequency distribution and bandwidth; The calculation formula of fast Fourier transform is as follows: Where X(f) is the frequency component; x n is the nth sample value of the time domain signal; f is the frequency; N is the total number of samples; Frequency distribution: The frequency spectrum of the signal is obtained through FFT, so as to analyze the distribution of the main frequency components; Bandwidth describes the frequency range of a signal and is calculated as follows: Bandwidth = fhigh-flow Where, Bandwidth is the bandwidth; fhigh is the cutoff frequency of the high-frequency component in the spectrum; flow is the cutoff frequency of the low-frequency component in the spectrum; Step 4.3, time-frequency domain features: Short-time Fourier transform (STFT) is used to obtain the joint information of time and frequency and capture the instantaneous characteristics of lightning strikes. The calculation formula of short-time Fourier transform STFT is as follows: Where X(t,f) is the signal component at time t and frequency f; x(τ) is the original signal; ω(τ-t) is the window function; e is the base of the natural logarithm, which is approximately equal to 2.71828; j is the imaginary unit; 2π is a constant; f is the frequency; τ is a variable with respect to time; Step 4.4, impulse response characteristics: Analyze the transient voltage and current response caused by lightning pulse to evaluate the impact of lightning on the grounding system; The transient response is used to describe the voltage and current changes of the system under pulse input. The calculation formula is as follows: R(t)=V(t) / I(t) Where R(t) is the equivalent resistance at time t; V(t) and I(t) are the voltage and current at time t respectively; The duration of the pulse from the beginning to the end is measured as the pulse width; the maximum voltage or current value of the pulse is the pulse peak value, which is used to quantify the impact intensity of the lightning strike.

8. The method for performing lightning protection analysis through tower grounding resistance according to claim 5, characterized in that: In step 5, the anti-lightning model is a statistical model, which uses multivariate regression analysis to analyze the relationship between the grounding resistance and environmental factors before and after the lightning strike to infer the response mode of the grounding resistance to the lightning strike; Select the influencing factors of ground resistance as independent variables and the ground resistance value as dependent variable, construct a multivariate regression equation, fit the relationship between ground resistance and environmental factors under lightning events, and thus construct a multivariate regression model; The multivariate regression equation is as follows: R=β0+β1X1+β2X2+...+β n X n +e Where R is the grounding resistance; X1, X2, ...X n are different influencing factors; β0 is the bias term, β1, β2, …β n is the regression coefficient; ε is the error term; Use the least squares method to solve the regression coefficient β value, minimize the error sum of squares, estimate the influence of various factors on ground resistance, and achieve model fitting and parameter estimation; Use goodness of fit R 2 Test the explanatory power of the model, use significance test to analyze whether each factor has a significant impact on ground resistance, and realize model verification and inference; Input environmental factor values, predict the change of grounding resistance under lightning strike, evaluate the lightning resistance of the grounding system under different environments, and realize the predictive application of the model.

9. The method for performing lightning protection analysis through tower grounding resistance according to claim 5, characterized in that: In step 5, the characteristics of the ground resistance data of each tower are analyzed and evaluated, including: calculating the recovery time, stabilization time, and resistance change after recovery of the ground resistance after the lightning strike event, so as to evaluate the lightning resistance recovery capability of the grounding system; The recovery time is the time interval from the occurrence of the lightning strike to the recovery of the ground resistance to a steady state, and the calculation formula is as follows: T recovery =t recovered -t event Where, T recovery is the recovery time; t recovered is the time point when the resistance returns to the steady state; t event is the time point when the lightning strike occurred; The stabilization time is the time interval during which the resistance reaches and remains at a stable value during the recovery time. The calculation formula is as follows: T stable =t stable end -t stable start Where, T stable is the stabilization time; t stable end The time it takes for the resistance to enter the stable range; t stable start To keep the resistance at the end of the stable range; The resistance change is the peak change of ground resistance caused by the lightning strike event, and the calculation formula is as follows: ΔR=R peak -R baseline Where ΔR is the resistance change; R peak is the instantaneous resistance peak value of lightning strike; R baseline is the steady-state resistance value before the lightning strike.

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