Grounding resistance regular monitoring system and method

Abstract

The invention discloses a grounding resistance regular monitoring system and method, and belongs to the technical field of power equipment state monitoring. The system comprises a pulse generation module, a measurement module, a control module, a protection module and a communication module. The core lies in that a low-amplitude short-time-range direct-current pulse current is adopted to be injected into a grounding system, the pulse amplitude, width and frequency parameters are optimized to be always lower than the action threshold value of a relay protection device, and therefore accurate measurement is achieved on the premise that power is not cut off and misoperation is not caused. Meanwhile, historical data trend analysis and soil environment factors are fused, the deterioration trend of the grounding resistance is intelligently predicted, early warning is performed in advance, and a resistance reduction device can be linked for automatic adjustment. The method effectively solves the problems that a traditional measurement method needs power failure and is poor in interference resistance and an existing online monitoring technology is likely to trigger protection by mistake, and achieves safe, accurate, automatic and intelligent monitoring, operation and maintenance of the grounding resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power equipment state monitoring, and particularly relates to a grounding resistance periodic monitoring system and method. BACKGROUND

[0002] In key facilities such as power systems, communication base stations and lightning protection grounding, the stability of the grounding resistance is directly related to the safety of equipment and personal protection. Traditional grounding resistance measurement methods such as the three-pole method and the clamp meter method usually require power-off operation, which not only affects the continuity of power supply, but also cannot realize long-term and continuous dynamic monitoring. With the popularization of smart grids and unattended sites, the demand for real-time, online and non-destructive monitoring of grounding resistance is increasing. However, in existing online monitoring technologies, the AC small signal injection method is easily disturbed by power frequency, resulting in a decrease in measurement accuracy; the DC measurement method causes data deviation due to the polarization effect of the grounding electrode, and it is difficult to meet the requirements of high accuracy and long-term stability. In addition, if the monitoring process mistakenly triggers relay protection devices such as RCD and differential protection, it will cause system misoperation and seriously affect the stable operation of the power grid; therefore, how to realize accurate, safe and automated monitoring of the grounding resistance under the premise of uninterrupted power supply and without disturbing the system protection has become a technical problem to be solved in the field.

[0003] To solve the above problems, there are several attempts in existing technologies. One type is a monitoring scheme based on AC signal injection, which measures the response voltage and current to calculate the resistance value by injecting a specific frequency AC signal into the grounding system. Although this method can realize online measurement, it is easily disturbed by power frequency and harmonic interference, and the measurement stability is poor. Another type is a measurement method based on DC signal, which measures the voltage drop by applying a DC current to calculate the resistance, but the DC current will cause polarization of the grounding electrode, and the measurement error will gradually increase after long-term use. In recent years, the pulse current method has been gradually introduced into this field, which uses transient pulses to reduce polarization effects and can measure under uninterrupted power supply conditions. However, if the amplitude or frequency of the conventional pulse current is not properly set, it may still mistakenly trigger the relay protection device, causing system misoperation, which limits its application in actual engineering.

[0004] Although the existing pulse current monitoring scheme avoids the problems of polarization effect and power-off measurement to some extent, it still has significant defects: 1. The pulse parameters are not optimized, which easily reaches the trigger threshold of the relay protection device, and there is a risk of misoperation; 2. Lack of intelligent adjustment and anti-interference mechanism, which is difficult to adapt to complex power grid environments; 3. Unable to form a linkage with grounding system maintenance methods, and unable to realize closed-loop control; therefore, a grounding resistance periodic monitoring system and method are needed to solve the above problems. SUMMARY

[0005] The technical problems to be solved by the present application are to provide a grounding resistance periodic monitoring system and method, to continuously monitor the grounding resistance without interference and with high precision by optimizing the amplitude, pulse width and frequency of the pulse current to be always lower than the triggering threshold of the relay protection, introducing intelligent monitoring, anti-interference mechanism and data analysis function, and dynamically adjusting the resistance reduction equipment, thereby improving the system reliability and intelligent operation level.

[0006] To solve the above technical problems, the technical solution adopted by the present application is: The grounding resistance periodic monitoring system comprises: A pulse generation module for generating a low-amplitude, short-duration direct current pulse current; the pulse amplitude , pulse width and pulse frequency are set according to the characteristics of the target grounding system and the triggering threshold of the relay protection device; A measurement module for collecting the voltage response signal U and the current response signal I generated when the direct current pulse current is injected into the grounding loop; A control module connected with the pulse generation module and the measurement module for controlling the output parameters of the pulse generation module and calculating the grounding resistance value based on the voltage response signal U and the current response signal I; A protection module connected with the pulse generation module for ensuring that the pulse current amplitude output by the pulse generation module is always lower than the preset safety threshold through a hardware limiting circuit; A communication module connected with the control module for transmitting the grounding resistance value and system state information to a remote monitoring platform.

[0007] Preferably, the amplitude , pulse width and pulse frequency of the direct current pulse current output by the pulse generation module meet the following conditions: ; Wherein, is the current triggering threshold of the relay protection device, is the time triggering threshold, is the power frequency, n is a positive integer.

[0008] Preferably, the control module is used to perform resistance degradation prediction based on trend extrapolation and failure physical model, specifically including: A data sequence construction unit for storing historical grounding resistance measurement values in chronological order , forming time series data; a trend fitting unit configured to fit a baseline trend function of the resistance value over time based on the time series data using a weighted moving average method or a linear regression method ; a prediction unit configured to extrapolate the baseline trend function to a future time point to obtain a base prediction value ; an acceleration factor correction unit configured to introduce one or more environmental acceleration factors to correct the base prediction value, the environmental acceleration factors being calculated based on real-time or historical environmental data, to obtain a final resistance prediction value calculated by the following formula: ; wherein, is the jth environmental acceleration factor, is a weight coefficient corresponding to the jth environmental acceleration factor; a warning decision unit configured to compare the corrected prediction value with a preset warning threshold , and if , a warning signal is generated.

[0009] Preferably, the environmental acceleration factors include at least one of a soil corrosivity factor and an electrical stress factor ; the soil corrosivity factor is calculated based on soil humidity , soil pH or soil temperature data received by the communication module or measured by a local sensor; and the electrical stress factor is calculated based on historical leakage current effective value or pulse current cumulative flux recorded by the measurement module.

[0010] Preferably, a resistance reduction linkage module is further included and connected to the control module; when the control module determines that the current grounding resistance value exceeds an action threshold , the control module starts a resistance reduction device through the resistance reduction linkage module for dynamic adjustment.

[0011] Preferably, the control module controls the pulse generation module to inject a pulse sequence at random time intervals to avoid synchronization with periodic interference signals.

[0012] ​Further, the injection timing of the direct current pulse current is randomly spaced or fixed period, so as to avoid superposition with power frequency signal.

[0013] Preferably, a grounding resistance periodic monitoring method using the grounding resistance periodic monitoring system, comprising the following steps: Parameter setting step: setting the output pulse amplitude, pulse width and pulse frequency of the pulse generation module by the control module according to the pre-stored relay protection threshold And power frequency of the power grid , and ensuring ; Pulse injection and measurement step: injecting direct current pulse current meeting the above parameters into the grounding system through the pulse generation module, and collecting the voltage response UU and current response I of the grounding loop through the measurement module; Calculation step: calculating the grounding resistance value by the control module according to the following formula : ; ; Wherein, U is the voltage response value collected by the measurement module, and I is the current response value collected by the measurement module; Data transmission step: uploading the calculated grounding resistance value to the remote monitoring platform through the communication module.

[0014] Preferably, it further comprises a failure physics-based early warning step: The control module calls the historical grounding resistance data sequence ; Trend fitting is performed on the data sequence to obtain a baseline trend function ; The baseline trend function is extrapolated to obtain the basic prediction value at the future time point ; One or more environmental acceleration factors are obtained , and the final resistance prediction value is calculated by the following formula : ; If , maintenance warning information is generated and sent.

[0015] Preferably, the environmental acceleration factor includes soil corrosivity factor and electrical stress factor ; the soil corrosivity factor is determined according to soil humidity and soil pH value​pH The calculation is as follows: ; wherein is the optimal humidity value, is the neutral pH value, and are proportional coefficients; The electrical stress factor According to the total flux of the injected pulse current within the monitoring period The calculation is as follows: ; wherein is the proportional coefficient.

[0016] Preferably, the method further comprises a linkage control step: The control module compares the calculated current grounding resistance value with a preset action threshold value ; If , the control module starts the resistance reduction device through the resistance reduction linkage module until the resistance value returns to the normal range.

[0017] Further, in the parameter setting step, the control module can dynamically adjust the pulse parameters according to the received remote instructions or system self-learning results to adapt to different grounding environments or relay protection configurations.

[0018] The beneficial effects of the present application are as follows: 1. The present application effectively avoids the polarization effect in traditional DC measurement by adopting low-amplitude, short-time DC pulse current injection technology and combining pulse parameter optimization design, significantly improving the measurement accuracy of grounding resistance. At the same time, by strictly controlling the pulse current amplitude and time parameters below the trigger threshold of the relay protection device, the system misoperation caused by monitoring behavior is fundamentally eliminated, ensuring the continuity and stability of the power grid operation.

[0019] 2. The present application introduces an intelligent monitoring and adaptive adjustment mechanism, the system can automatically execute measurement tasks regularly, and based on historical data, trend analysis and early warning are performed, realizing long-term, dynamic, and intelligent management of the grounding resistance state. This method not only reduces manual intervention and improves operation efficiency, but also can detect potential faults in advance and avoid equipment damage or safety accidents caused by grounding system failure.

[0020] 3. This invention, by incorporating anti-interference and safety protection modules and employing high-frequency narrow pulse or random interval triggering methods, effectively avoids power frequency interference and harmonic effects, thereby improving the accuracy of signal acquisition. Simultaneously, the system possesses a linkage function with resistance reduction devices, automatically activating an adjustment mechanism when excessive resistance is detected, forming a closed-loop control of monitoring-judgment-execution. This significantly enhances the system's practicality and reliability, making it suitable for grounding status management of various critical facilities such as power, communication, and rail transit. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the system framework of the present invention; Figure 2 This is a schematic diagram of the control module of the present invention; Figure 3 This is a schematic diagram of the process method in an embodiment of the present invention; Figure 4 This is a comparison graph of two methods in the embodiments of the present invention and the prior art. Detailed Implementation

[0022] Example 1: like Figure 1 As shown, the grounding resistance periodic monitoring system includes: The pulse generation module is used to generate low-amplitude, short-duration DC pulse currents; its pulse amplitude... Pulse width and pulse frequency The settings are based on the characteristics of the target grounding system and the trigger threshold of the relay protection device; the measurement module is used to acquire the voltage response signal U and the current response signal I generated when the DC pulse current is injected into the grounding circuit; the control module is connected to the pulse generation module and the measurement module, and is used to control the output parameters of the pulse generation module and calculate the grounding resistance value based on the voltage response signal U and the current response signal I. A protection module, connected to the pulse generation module, is used to ensure the amplitude of the output pulse current through a hardware limiting circuit. Always below the preset safety threshold A communication module, connected to the control module, is used to transmit the grounding resistance value. The system status information is transmitted to the remote monitoring platform. In specific implementation, by adopting low-amplitude, short-duration DC pulse current injection technology and combining it with pulse parameter optimization design, the polarization effect in traditional DC measurement is effectively avoided, and the measurement accuracy of grounding resistance is significantly improved.

[0023] Preferably, the amplitude of the DC pulse current output by the pulse generation module is... Pulse width Pulse frequency The following conditions must be met: ; in, The current trigger threshold of the relay protection device. The time-triggered threshold, For power grid frequency, n It is a positive integer; in specific implementation, by strictly controlling the pulse current amplitude and time parameter trigger threshold of the relay protection device, the system malfunction caused by monitoring behavior is fundamentally eliminated, ensuring the continuity and stability of power grid operation.

[0024] like Figure 2 As shown, preferably, the control module is used to perform resistance degradation prediction based on trend extrapolation and a failure physical model, specifically including: Data sequence construction unit: used to store historical grounding resistance measurements in chronological order. This forms time series data; Trend Fitting Unit: Used to fit a baseline trend function of resistance value changing over time based on the time series data, using either a weighted moving average method or a linear regression method. ; Prediction unit: used to convert the baseline trend function Extrapolation to future time points Obtain the basic predicted value ; Acceleration Factor Correction Unit: Used to introduce one or more environmental acceleration factors. The environmental acceleration factor is adjusted by correcting the baseline prediction. The final predicted resistance value is calculated based on real-time or historical environmental data. Calculated by the following formula: ; in, Let j be the environmental acceleration factor. The weight coefficient corresponding to the j-th environmental acceleration factor; Early warning decision unit: used to process the corrected predicted value With the preset warning threshold If a comparison is made, If the system generates an early warning signal, it can automatically perform measurement tasks periodically and conduct trend analysis and early warning based on historical data by introducing intelligent monitoring and adaptive adjustment mechanisms. This enables long-term, dynamic, and intelligent management of the grounding resistance status. It not only reduces manual intervention and improves operation and maintenance efficiency, but also detects potential faults in advance and avoids equipment damage or safety accidents caused by grounding system failure.

[0025] Preferably, the environmental acceleration factor comprises at least one of a soil corrosive factor and an electrical stress factor ; the soil corrosive factor is based on the soil humidity , soil pH or soil temperature measured by the communication module or local sensors ; the electrical stress factor is based on the historical leakage current effective value or impulse current cumulative flux recorded by the measurement module .

[0026] Preferably, it further comprises a resistance reduction linkage module connected to the control module; when the control module determines that the current grounding resistance value exceeds the action threshold , it starts the resistance reduction device through the resistance reduction linkage module for dynamic adjustment; in specific implementation, the anti-interference and safety protection module adopts high-frequency narrow pulse or random interval triggering mode, which can effectively avoid power frequency interference and harmonic influence, and improve the accuracy of signal acquisition.

[0027] Preferably, the control module controls the pulse generation module to inject pulse sequences at random time intervals to avoid synchronization with periodic interference signals.

[0028] Further, the injection time of the direct current pulse current is random interval or fixed period to avoid superposition with power frequency signals; in specific implementation, the system realizes automatic start of the adjustment mechanism when it detects that the resistance is out of standard through the linkage function of the resistance reduction device, forms a closed-loop control of monitoring-judgment-execution, and enhances the practicability and reliability of the system.

[0029] Embodiment two: As shown in the figure, the embodiment provides a grounding resistance regular monitoring method using the grounding resistance regular monitoring system, comprising the following steps: Figure 3 Parameter setting step: the control module sets the amplitude , pulse width and pulse frequency of the output pulse of the pulse generation module according to the pre-stored relay protection threshold and power frequency , and ensures ; ; Pulse injection and measurement step: the pulse generation module injects direct current pulse current meeting the above parameters into the grounding system, and the measurement module collects the voltage response UU and current response I of the grounding loop at the same time; Computing step: the ground resistance value is calculated by the control module according to the following formula : ; Wherein, U is the voltage response value collected by the measuring module, and I is the current response value collected by the measuring module; Data transmission step: the calculated ground resistance value is uploaded to the remote monitoring platform by the communication module.

[0030] Preferably, it further comprises a failure physics-based early warning step: The control module calls the historical ground resistance data sequence ; Trend fitting is performed on the data sequence to obtain a baseline trend function ; The baseline trend function is extrapolated to obtain the basic prediction value of the future time point ; One or more environmental acceleration factors are obtained , and the final resistance prediction value is calculated using the following formula : ; If , a maintenance warning message is generated and sent.

[0031] Preferably, the environmental acceleration factor includes a soil corrosivity factor and an electrical stress factor ; the soil corrosivity factor is calculated according to the soil humidity and the soil pH value pH , and the calculation formula is: ; Wherein is the optimal humidity value, is the neutral pH value, and are proportional coefficients; The electrical stress factor is calculated according to the total flux of the injected pulse current within the monitoring period , and the calculation formula is: ; Wherein is a proportional coefficient.

[0032] Preferably, it further comprises a linkage control step: The control module uploads the calculated current ground resistance value to the remote monitoring platform ​​comparing the measured value of the resistance with a preset action threshold value comparing the measured value of the resistance with a preset action threshold value comparing the measured value of the resistance with a preset action threshold value If the measured value of the resistance is greater than the action threshold value, the control module starts the resistance reduction device through the resistance reduction linkage module until the resistance value returns to the normal range.

[0033] Further, in the parameter setting step, the control module can dynamically adjust the pulse parameters according to the received remote instructions or system self-learning results to adapt to different grounding environments or relay protection configurations.

[0034] Embodiment three: This embodiment provides a scheme for periodic monitoring of the grounding grid of the substation of the Yunnan Mile Xifeng wind power plant, and the specific implementation process is as follows: Using the grounding resistance periodic monitoring system, set the pulse parameters: amplitude Ip =25 mA , pulse width tp =8 ms , frequency fp =7 Hz , random interval triggering; the system automatically measures once a day and continuously monitors the soil humidity Sm and records the pulse flux Q total for trend prediction; the actual running data are shown in Table 1: Table 1: Measured value and predicted value of the resistance of the grounding resistance of the substation of the wind power plant in 2024

[0035] From Table 1 above, the actual running value and the predicted value have a very small difference, and the deviation caused by the influence of soil humidity is also within the control range.

[0036] Before maintenance on April 12, the traditional method including the traditional three-pole method and the alternating current injection method were used to verify the measurement compared with the method of the present scheme, and the results are shown in Table 2: Table 2: Comparison of data verification with the prior art

[0037] From Table 2 above and Figure 4It can be known that the grounding resistance periodical monitoring system and method provided by the scheme exhibits significant advancement compared with the prior art. Firstly, in terms of functionality, the scheme realizes non-power-off and automatic daily monitoring, while the traditional three-pole method can only rely on manual single measurement with power-off and cannot obtain continuous data trend. Secondly, in terms of accuracy, the pulse injection method adopted by the scheme effectively avoids the defect that the alternating current injection method is easily disturbed by power frequency and harmonic, and the measurement value 0.63 Omega is closer to the authoritative value 0.65 Omega of the traditional three-pole method, while the measurement value of the alternating current injection method is seriously deviated due to the interference, which is 0.71 Omega. Most importantly, in terms of early warning capability, the intelligent prediction model by fusing soil humidity data and historical trend early warns for the first time 21 days before the maintenance on March 22, realizes the fundamental change of the operation and maintenance mode from post-maintenance to pre-warning, provides sufficient time window for arranging planned maintenance, and greatly improves the safety and reliability of the power grid system.

Claims

1. A grounding resistance periodic monitoring system, characterized in that, include: The pulse generation module is used to generate low-amplitude, short-duration DC pulse currents. Its pulse amplitude Pulse width and pulse frequency The settings are based on the characteristics of the target grounding system and the triggering threshold of the relay protection device; The measurement module is used to acquire the voltage response signal U and the current response signal I generated when the DC pulse current is injected into the grounding circuit; The control module, connected to the pulse generation module and the measurement module, is used to control the output parameters of the pulse generation module and calculate the grounding resistance value based on the voltage response signal U and the current response signal I. ; The protection module, connected to the pulse generation module, is used to ensure the amplitude of the output pulse current through a hardware limiting circuit. Always below the preset safety threshold ; A communication module, connected to the control module, is used to transmit the grounding resistance value. The system status information is transmitted to the remote monitoring platform.

2. The grounding resistance periodic monitoring system according to claim 1, characterized in that, The amplitude of the DC pulse current output by the pulse generation module Pulse width Pulse frequency The following conditions must be met: ； in, The current trigger threshold of the relay protection device. The time-triggered threshold, For power grid frequency, n It is a positive integer.

3. The grounding resistance periodic monitoring system according to claim 1, characterized in that, The control module is used to perform resistance degradation prediction based on trend extrapolation and failure physical models, specifically including: Data sequence construction unit: used to store historical grounding resistance measurements in chronological order. This forms time series data; Trend Fitting Unit: Used to fit a baseline trend function of resistance value changing over time based on the time series data, using either a weighted moving average method or a linear regression method. ; Prediction unit: used to convert the baseline trend function Extrapolation to future time points Obtain the basic predicted value ; Acceleration Factor Correction Unit: Used to introduce one or more environmental acceleration factors. The environmental acceleration factor is adjusted by correcting the baseline prediction. The final predicted resistance value is calculated based on real-time or historical environmental data. Calculated by the following formula: ； in, Let j be the environmental acceleration factor. The weight coefficient corresponding to the j-th environmental acceleration factor; Early warning decision unit: used to process the corrected predicted value With the preset warning threshold If a comparison is made, If so, an early warning signal will be generated.

4. The grounding resistance periodic monitoring system according to claim 3, characterized in that, The environmental acceleration factor Including soil erosion factors and electrical stress factor At least one of the following; soil erosion factors Soil moisture received by the communication module or measured by local sensors Soil pH or soil temperature The data was calculated. Electrical stress factor Based on the historical RMS values ​​of leakage current recorded by the measurement module or pulse current cumulative flux The calculation yielded the result.

5. The grounding resistance periodic monitoring system according to claim 4, characterized in that, It also includes a resistance reduction linkage module, which is connected to the control module; the control module determines the current grounding resistance value. Exceeding the action threshold At that time, the drag reduction device is activated through the drag reduction linkage module for dynamic adjustment.

6. The grounding resistance periodic monitoring system according to claim 1, characterized in that, The control module controls the pulse generation module to generate pulses at random time intervals. Inject pulse sequences to avoid synchronization with periodic interference signals.

7. A method for periodically monitoring grounding resistance, characterized in that, The grounding resistance periodic monitoring system according to any one of claims 1 to 6 includes the following steps: Parameter setting steps: The control module sets the parameters according to the pre-stored relay protection thresholds. and power grid frequency Set the amplitude of the output pulse of the pulse generation module. Pulse width and pulse frequency and ensure ; Pulse injection and measurement steps: A DC pulse current that meets the above parameters is injected into the grounding system through the pulse generation module, and the voltage response UU and current response I of the grounding loop are collected through the measurement module. Calculation steps: The control module calculates the grounding resistance value according to the following formula. : ； Where U is the voltage response value acquired by the measurement module, and I is the current response value acquired by the measurement module; Data transmission steps: The calculated grounding resistance value is transmitted via the communication module. Uploaded to the remote monitoring platform.

8. The method for periodically monitoring grounding resistance according to claim 7, characterized in that, It also includes early warning steps based on failure physics: The control module retrieves historical grounding resistance data sequences. ; The data sequence is subjected to trend fitting to obtain a baseline trend function. ; Extrapolating the baseline trend function yields future time points. Baseline forecast ; Obtain one or more environmental acceleration factors The final predicted resistance value is calculated using the following formula. : ； like Then, maintenance warning information will be generated and sent.

9. The method for periodically monitoring grounding resistance according to claim 8, characterized in that, The environmental acceleration factor Including soil erosion factors and electrical stress factor Soil corrosive factors According to soil moisture and soil pH pH The calculation formula is as follows: ； in The optimal humidity value, The pH value is neutral. and This is the proportionality coefficient; The electrical stress factor Based on the total pulse current flux injected during the monitoring period The calculation formula is as follows: ； in This is the proportionality coefficient.

10. The method for periodically monitoring grounding resistance according to claim 7, characterized in that, It also includes linkage control steps: The control module will calculate the current grounding resistance value. With preset action threshold Compare; like If the resistance value returns to the normal range, the control module will activate the resistance reduction device through the resistance reduction linkage module.

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