Alternating current insulator leakage current simulation and direct current extraction method and system

Abstract

The invention discloses an AC insulator leakage current simulation and DC extraction method and system, and relates to the technical field of power system insulation detection and signal processing, and the method comprises the steps: building a controlled wetting experiment platform based on a data collection device, a slope method test device and a sensor; collecting a leakage current signal under a constant alternating current voltage, and eliminating high-frequency noise by adopting moving average filtering; identifying arc intervals through time domain threshold segmentation, spectrum energy distribution analysis and dynamic feature matching in a combined manner, and removing the arc intervals; sliding window median filtering is performed on the remaining signal to eliminate baseline drift, pure wetting leakage current is extracted, and a direct current component is extracted through FFT analysis and content is estimated. According to the invention, high-precision simulation, signal separation and direct current extraction of the leakage current are realized, the arc identification accuracy and the direct current detection sensitivity are remarkably improved, and a reliable basis is provided for quantitative diagnosis of wetting, pollution and aging states of the surface of the insulator.

Description

Technical Field

[0001] This invention relates to the field of signal processing technology, and in particular to a method for simulating AC insulator leakage current and extracting DC current. Background Technology

[0002] AC insulators are crucial components in power systems, supporting conductors and providing electrical insulation. During long-term operation, their surfaces are susceptible to environmental factors such as moisture, salt spray, and dust, forming a contamination layer or water film. This can lead to increased leakage current and even flashover accidents. The waveform and amplitude characteristics of the leakage current reflect the degree of wettability, contamination status, and discharge behavior of the insulator surface. Therefore, accurate acquisition and analysis of leakage current characteristics are essential for assessing insulation performance and enabling early fault diagnosis.

[0003] Existing research often employs time-domain analysis, frequency-domain analysis, and experimental simulation to characterize leakage current. Time-domain methods typically determine the wetting or discharge state by monitoring changes in the waveform, peak value, and RMS value of the leakage current; however, they are easily affected by environmental noise and transient interference, making it difficult to distinguish between wetting leakage current and arc discharge signals. Frequency-domain analysis methods utilize Fourier transform or wavelet transform to decompose the signal and identify arc discharge characteristics through high-frequency energy changes; however, they mostly focus on transient analysis during the flashover phase, with limited research on the spectral characteristics of stable leakage current during the wetting phase. Experimental simulation methods, such as the inclined plane method and the spray method, can reproduce the wetting and discharge processes on the insulator surface; however, existing devices have limited signal sampling accuracy and synchronization, making it difficult to capture weak DC components or spatial consistency characteristics among multiple sensors.

[0004] Existing technologies generally suffer from the following shortcomings: arc discharge and wetting leakage current alternate in time, resulting in complex waveform superposition, making it difficult to effectively separate them using traditional thresholding or filtering methods; high-frequency noise and baseline drift still exist in the signal, leading to large errors in DC component extraction and failing to accurately reflect changes in the conductivity characteristics of the insulator surface; and the lack of a comprehensive analysis framework combining time domain, frequency domain, feature matching, and multi-sensor verification results in low arc identification accuracy and difficulty in obtaining pure wetting leakage current. Summary of the Invention

[0005] In view of the aforementioned existing problems, the present invention is proposed.

[0006] Therefore, this invention provides a method for simulating AC insulator leakage current and extracting DC components to solve the problems of inaccurate arc interval identification, difficulty in eliminating signal baseline drift, and insufficient accuracy in extracting DC components.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for simulating AC insulator leakage current and extracting DC current, comprising: An experimental platform was built based on a data acquisition device, an inclined plane method experimental device, and sensors.

[0008] Leakage current was collected by applying an AC voltage under controlled wetting conditions using the inclined plane method, and the collected leakage current signal was then processed by moving average filtering.

[0009] The arc intervals were identified and eliminated by using time-domain threshold segmentation, spectral energy distribution analysis, and dynamic feature matching. Stable wetting leakage current was then extracted after filtering and spectral verification.

[0010] FFT analysis was performed on the wetting leakage current to extract the DC component and estimate its content.

[0011] As a preferred embodiment of the AC insulator leakage current simulation and DC extraction method of the present invention, the construction of the test platform includes connecting a data acquisition device to a current sensor to detect weak DC components, and achieving multi-channel synchronous acquisition by connecting multiple sensors to the data acquisition device.

[0012] The inclined plane test device simulates the wetting process of the insulator surface under controllable conditions. By forming a continuous water film through constant flow of dripping liquid, it reproduces the actual working conditions of leakage current generation and arc discharge, providing a stable and repeatable experimental environment for the acquisition and analysis of leakage current signals.

[0013] As a preferred embodiment of the AC insulator leakage current simulation and DC extraction method of the present invention, the leakage current acquisition via the inclined plane method includes: placing the insulator sample on the inclined plane structure; covering the upper electrode with filter paper and connecting it to a peristaltic pump; the peristaltic pump dripping solution onto the filter paper at a constant flow rate, saturating the filter paper to form a continuous fine stream, simulating the wetting of the insulator surface, and forming a leakage circuit; connecting the lower electrode to the insulating material; and applying a constant AC voltage between the upper and lower electrodes to form a controlled wetting environment; after applying the voltage, synchronously acquiring the leakage current signal and storing the original data; and using a moving average filter to eliminate high-frequency noise and retain low-frequency characteristics.

[0014] As a preferred embodiment of the AC insulator leakage current simulation and DC extraction method of the present invention, the method of identifying and eliminating arc intervals includes: using a time-domain threshold segmentation method to initially screen arc current intervals; continuously monitoring the collected leakage current signal; and marking the sampling time corresponding to the leakage current time series as the arc start point when the current change rate exceeds a preset multiple threshold. The arc start point is used to identify the moment when the current changes abruptly and rises rapidly. in, The rate of change of current; is the threshold coefficient for the rate of change of current, which is a dimensionless coefficient with a value range of 1.5 to 2.5; This is the effective value of the leakage current; When the instantaneous current amplitude gradually decreases from the peak stage of the arc, and satisfies: in, This represents the instantaneous current amplitude. This is the effective value of the leakage current; The amplitude reduction factor is taken as 0.2 to 0.3; The sampling time corresponding to the leakage current time series is marked as the arc termination point, which is used to identify the moment when the current amplitude drops and tends to a steady state. Based on the arc start and end points, the arc segment is accurately extracted from the original leakage current signal, and the arc duration, peak current and energy characteristic parameters are extracted. By setting a minimum duration threshold, short-time noise is eliminated, and the arc current range is effectively identified. The spectral energy distribution analysis to verify the arc characteristics includes performing FFT analysis on the leakage current signal to obtain the power spectral density of each frequency band; calculating the energy proportion of the power spectral density in the high-frequency band from 1 kHz to 50 kHz; when the high-frequency energy proportion is not less than a preset threshold of 10%, and the amplitude of the power frequency component decays to less than 50% relative to the steady-state value, the time period is determined to be the arc interval; based on the determination result of the spectral analysis, the time interval of the arc occurrence is output to provide a basis for subsequent signal rejection and wetting leakage current extraction.

[0015] As a preferred embodiment of the AC insulator leakage current simulation and DC extraction method of the present invention, the dynamic feature matching includes: extracting waveform features, including rise time and fall time, from the obtained arc interval and matching them with a preset template library based on cosine similarity. The preset template library consists of arc current waveform samples collected experimentally and generated by simulation. The samples are normalized and clustered to form multiple representative templates, which are used to determine the arc attribute of candidate signal intervals based on waveform cosine similarity or cross-correlation during the signal recognition stage. When the cosine similarity between the candidate interval waveform and the arc template is not less than 0.8, it is determined to be an arc interval and is eliminated. Based on the determined candidate arc intervals, the synchronization and amplitude consistency of the upper and lower electrode currents are verified by multiple sensors. If the cross-correlation time delay of the upper and lower electrode current signals does not exceed 1 ms according to the time synchronization criterion and the ratio of the peak value or effective value of the upper and lower electrode current signals is in the range of 0.5 to 2.0 according to the amplitude consistency criterion, the candidate interval is confirmed to be an arc interval and is eliminated. Otherwise, it is determined to be a non-arc interference signal and is not eliminated.

[0016] As a preferred embodiment of the AC insulator leakage current simulation and DC extraction method of the present invention, the wetting leakage current extraction includes: after eliminating the arc interval, performing sliding window mid-range filtering on the remaining signal to eliminate baseline drift, wherein the width of the sliding window is 50 ms, to obtain the wetting leakage current; and performing FFT verification on the wetting leakage current, wherein when the high-frequency energy ratio is less than 5% and the power frequency component amplitude fluctuation does not exceed ±10%, the signal is confirmed to be stable and used as a pure wetting leakage current for subsequent DC component extraction.

[0017] As a preferred embodiment of the AC insulator leakage current simulation and DC extraction method of the present invention, the DC component extraction and content estimation includes: performing FFT analysis on the extracted wetting leakage current signal, converting the time domain signal into a frequency domain signal, obtaining the amplitude distribution of different frequency components; extracting the amplitude of the component corresponding to the frequency of 0 Hz as the amplitude of the DC component, and calculating the proportion of the DC component; in, The percentage of DC component; This represents the amplitude of the DC component. This is the effective value of the current.

[0018] Secondly, the present invention provides an AC insulator leakage current simulation and DC extraction system, including a test platform construction module: a test platform is constructed based on a data acquisition device, an inclined plane method test device, and sensors.

[0019] Signal preprocessing module: The leakage current is collected by applying AC voltage under controlled wetting conditions using the inclined plane method, and the collected leakage current signal is processed by moving average filtering.

[0020] Arc identification and rejection module: The arc interval is identified and rejected by means of time-domain threshold segmentation, spectrum energy distribution analysis and dynamic feature matching. Stable wetting leakage current is extracted after filtering and spectrum verification.

[0021] DC component extraction module: Performs FFT analysis on wetting leakage current to extract DC component and estimate its content.

[0022] Thirdly, the present invention provides a computer device including a memory and a processor, wherein the memory stores a computer program, wherein when the computer program is executed by the processor, it implements any step of the AC insulator leakage current simulation and DC extraction method as described in the first aspect of the present invention.

[0023] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, it implements any step of the AC insulator leakage current simulation and DC extraction method as described in the first aspect of the present invention.

[0024] The beneficial effects of this invention are as follows: By constructing a controlled wetting test platform based on the inclined plane method, and combining high-sampling-rate data acquisition with multi-sensor synchronous monitoring, this invention achieves high-precision simulation and analysis of leakage current in AC insulators. By introducing a joint judgment mechanism of time-domain threshold segmentation, spectral energy distribution analysis, and dynamic feature matching, it can accurately identify and eliminate arc intervals, effectively avoiding the influence of arc interference on leakage current measurement. By eliminating signal baseline drift through sliding window midpoint filtering, the purity and stability of wetting leakage current extraction are significantly improved. FFT spectral analysis is used to extract the DC component, enabling quantitative evaluation of the conductivity characteristics of the insulator surface. This method achieves an organic combination of arc separation, signal filtering, and DC component extraction, significantly improving arc identification accuracy, DC component detection sensitivity, and result repeatability compared to existing technologies. It provides a reliable basis for the quantitative diagnosis of the wetting state and aging degree of insulator surfaces, and has high engineering application and research promotion value. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a flowchart of the AC insulator leakage current simulation and DC extraction method.

[0027] Figure 2 This is a schematic diagram of the inclined plane method test apparatus.

[0028] Figure 3 This is a schematic diagram of a typical leakage current waveform in the inclined plane method test.

[0029] Figure 4 This is a schematic diagram of the voltage and current waveforms during the wetting stage.

[0030] Figure 5 This is a schematic diagram of the frequency components of the wetting leakage current. Detailed Implementation

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0033] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0034] Example 1, referring to Figure 1 This is one embodiment of the present invention, which provides a method for simulating AC insulator leakage current and extracting DC current, including the following steps: S1: An experimental platform is built based on a data acquisition device, an inclined plane method experimental device, and sensors.

[0035] The construction of the test platform includes connecting a data acquisition device to a current sensor to detect weak DC components, and achieving multi-channel synchronous acquisition by connecting multiple sensors to the data acquisition device.

[0036] The inclined plane test device simulates the wetting process of the insulator surface under controllable conditions. By forming a continuous water film through constant flow of dripping liquid, it reproduces the actual working conditions of leakage current generation and arc discharge, providing a stable and repeatable experimental environment for the acquisition and analysis of leakage current signals.

[0037] S2: The leakage current is collected by applying an AC voltage under controlled wetting conditions using the inclined plane method, and the collected leakage current signal is then processed by moving average filtering.

[0038] The method of collecting leakage current by inclined plane includes placing an insulator sample on an inclined plane structure, covering the upper electrode with filter paper and connecting it to a peristaltic pump, and having the peristaltic pump drip solution onto the filter paper at a constant flow rate to saturate the filter paper and form a continuous fine stream, simulating the wetting of the insulator surface and forming a leakage circuit; connecting the lower electrode to the insulating material and applying a constant AC voltage between the upper and lower electrodes to form a controlled wetting environment; and simultaneously collecting leakage current signals and storing the raw data after applying the voltage.

[0039] High-frequency noise is eliminated by using a moving average filter. A fixed-width sliding window is set for the acquired leakage current time series signal. The average value of the sampling points in each window is calculated and replaced with the original sampling value at the center of the window. As the window slides point by point along the time axis, the high-frequency components with short-term abrupt changes are smoothed out, thereby reducing the influence of random noise. At the same time, the low-frequency variation trend of the leakage current is preserved, providing a stable input signal for subsequent arc interval identification and DC component extraction.

[0040] S3: The arc interval is identified and eliminated by time-domain threshold segmentation, spectral energy distribution analysis and dynamic feature matching. Stable wetting leakage current is extracted after filtering and spectral verification.

[0041] The process of identifying and eliminating arc intervals includes: initially screening arc current intervals using a time-domain threshold segmentation method; continuously monitoring the collected leakage current signal; and marking the sampling time corresponding to the leakage current time series as the arc start point when the current change rate exceeds a preset multiple threshold. The arc start point is used to identify the moment when the current changes abruptly and rises rapidly. in, The rate of change of current; is the threshold coefficient for the rate of change of current, which is a dimensionless coefficient with a value range of 1.5 to 2.5; This is the effective value of the leakage current; When the instantaneous current amplitude gradually decreases from the peak stage of the arc, and satisfies: in, This represents the instantaneous current amplitude. This is the effective value of the leakage current; The amplitude reduction factor is taken as 0.2 to 0.3; The sampling time corresponding to the leakage current time series is marked as the arc termination point, which is used to identify the moment when the current amplitude drops and tends to a steady state. Based on the arc start and end points, the arc segment is accurately extracted from the original leakage current signal, and the arc duration, peak current and energy characteristic parameters are extracted. By setting a minimum duration threshold, short-time noise is eliminated, and the arc current range is effectively identified. The spectral energy distribution analysis to verify the arc characteristics includes performing FFT analysis on the leakage current signal to obtain the power spectral density of each frequency band; calculating the energy proportion of the power spectral density in the high-frequency band from 1 kHz to 50 kHz; when the high-frequency energy proportion is not less than a preset threshold of 10%, and the amplitude of the power frequency component decays to less than 50% relative to the steady-state value, the time period is determined to be the arc interval; based on the determination result of the spectral analysis, the time interval of the arc occurrence is output to provide a basis for subsequent signal rejection and wetting leakage current extraction.

[0042] The dynamic feature matching includes extracting waveform features, including rise time and fall time, from the obtained arc interval and matching them with a preset template library based on cosine similarity. The preset template library consists of arc current waveform samples collected experimentally and generated by simulation. The samples are normalized and clustered to form multiple representative templates, which are used to determine the arc attribute of candidate signal intervals based on waveform cosine similarity or cross-correlation during the signal recognition stage. When the cosine similarity between the candidate interval waveform and the arc template is not less than 0.8, it is determined to be an arc interval and is eliminated. Based on the determined candidate arc intervals, the synchronization and amplitude consistency of the upper and lower electrode currents are verified by multiple sensors. If the cross-correlation time delay of the upper and lower electrode current signals does not exceed 1 ms according to the time synchronization criterion and the ratio of the peak value or effective value of the upper and lower electrode current signals is in the range of 0.5 to 2.0 according to the amplitude consistency criterion, the candidate interval is confirmed to be an arc interval and is eliminated. Otherwise, it is determined to be a non-arc interference signal and is not eliminated.

[0043] The wetting leakage current extraction includes: after removing the arc interval, performing a sliding window median filter on the remaining signal to eliminate baseline drift; inputting the leakage current signal after removing the arc interval into the median filter according to the time sequence; setting the sliding window width to 50 ms; sorting the sampling points according to the amplitude within each window; taking the sampling value located in the middle position as the output value of the window center point; and gradually replacing the sampling values ​​of the entire signal sequence as the window slides point by point along the time axis. This method effectively suppresses baseline shift caused by environmental drift or measurement noise, preserves the overall trend of the signal, and obtains a stable and pure wetting leakage current, providing accurate input for DC component extraction. The wetting leakage current signal after median filtering is verified by FFT to obtain the frequency domain power spectral density distribution. The power spectrum energy ratio in the high-frequency band from 1 kHz to 50 kHz is statistically analyzed, and the amplitude change of the power frequency component at 50 Hz in the entire spectrum is calculated. When the high-frequency energy ratio is less than 5% and the fluctuation of the power frequency component amplitude relative to the steady-state value does not exceed ±10%, the current signal spectrum structure is determined to be stable, indicating that it does not contain significant discharge or noise components, thus confirming that the signal can be used as a pure wetting leakage current for subsequent DC component extraction and analysis.

[0044] S4: Perform FFT analysis on the wetting leakage current, extract the DC component and estimate its content.

[0045] The extraction and estimation of the DC component includes performing FFT analysis on the extracted wetting leakage current signal to convert the time-domain signal into a frequency-domain signal and obtain the amplitude distribution of different frequency components; extracting the amplitude of the DC component with a frequency of 0 Hz and determining the proportion of the DC component; through this process, the quantitative analysis of the DC offset in the leakage current can be realized, reflecting the change in conductivity and the degree of contamination on the insulator surface, and providing a reliable basis for insulation performance evaluation.

[0046] in, The percentage of DC component; This represents the amplitude of the DC component. This is the effective value of the current.

[0047] This embodiment also provides an AC insulator leakage current simulation and DC extraction system, including: a test platform construction module: a test platform is constructed based on a data acquisition device, an inclined plane method test device, and sensors.

[0048] Signal preprocessing module: The leakage current is collected by applying AC voltage under controlled wetting conditions using the inclined plane method, and the collected leakage current signal is processed by moving average filtering.

[0049] Arc identification and rejection module: The arc interval is identified and rejected by means of time-domain threshold segmentation, spectrum energy distribution analysis and dynamic feature matching. Stable wetting leakage current is extracted after filtering and spectrum verification.

[0050] DC component extraction module: Performs FFT analysis on wetting leakage current to extract DC component and estimate its content.

[0051] This embodiment also provides a computer device applicable to the AC insulator leakage current simulation and DC extraction method, including: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to realize the AC insulator leakage current simulation and DC extraction method proposed in the above embodiment.

[0052] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0053] This embodiment also provides a storage medium storing a computer program, which, when executed by a processor, implements the method for simulating AC insulator leakage current and extracting DC current as proposed in the above embodiments. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0054] Example 2, refer to Figure 2-5 As an embodiment of the present invention, a method for simulating AC insulator leakage current and extracting DC current is provided. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0055] Artificial contaminant solution, consisting of an aqueous solution of 0.1% ammonium chloride and 0.02% nonionic wetting agent, was supplied at a constant flow rate of 0.6 mL / min using a peristaltic pump, ensuring a conductivity of 2.50 mS / cm at 23°C. The applied voltage was set to AC 4.5 kV. All samples were prepared into the standard shape of 120 × 50 × 6 mm³. Analysis of the collected data revealed that the DC component of the wetting current was approximately 10%, which is helpful in analyzing the mechanism of localized corrosion of the AC steel feet.

[0056] Figure 2 This is a schematic diagram of the inclined plane method test apparatus in an embodiment of the present invention. The apparatus mainly consists of an AC power supply, a voltage regulating transformer, a current limiting resistor R, an upper electrode, a lower electrode, a sample, filter paper, a peristaltic pump, an optical fiber probe, and a multi-channel spectrometer.

[0057] An AC power supply outputs an adjustable voltage via a voltage-regulating transformer, which is connected to the sample through a current-limiting resistor R to form a controlled AC voltage loop. The upper electrode is covered with filter paper and connected to a peristaltic pump. The pump drips solution onto the filter paper surface at a constant flow rate, saturating the filter paper and forming a continuous water film, thus simulating a wetted state on the surface of the insulator sample. The lower electrode is connected to the insulating material at the bottom of the sample, establishing a loop for leakage current. A fiber optic probe is used to collect discharge light signals that may be generated on the sample surface, while a multi-channel spectrometer and data acquisition system are used to simultaneously record current, voltage, and spectral data.

[0058] By constructing the aforementioned device, the wetting and discharge processes on the surface of an insulator can be simulated under controllable humidity and voltage conditions, enabling real-time acquisition and monitoring of leakage current. This device can stably reproduce the actual working conditions of wetting and arc discharge, providing reliable experimental data support for subsequent leakage current signal filtering, arc interval identification, and DC component extraction.

[0059] Figure 3 This diagram illustrates a typical leakage current waveform observed in the inclined plane method test of this invention. It demonstrates the time-domain variation characteristics of the leakage current on the surface of an AC insulator under controlled wetting conditions. As can be seen, with the formation of the water film and the occurrence of the discharge process, the leakage current fluctuates periodically along the time axis, exhibiting distinct arc discharge intervals at different stages. The current amplitude increases instantaneously and then rapidly decays to a steady state. This waveform reflects the alternating occurrence of arc discharge and wetting leakage current, providing experimental basis for arc interval identification and wetting leakage current extraction in this invention.

[0060] Figure 4This diagram illustrates the voltage and current waveforms during the wetting stage in an embodiment of the invention. It shows the phase and amplitude relationship between voltage and leakage current after a stable water film forms on the insulator surface under controlled wetting conditions. As can be seen, the voltage and current exhibit a generally sinusoidal pattern, with a smooth current waveform and stable amplitude, indicating that no significant discharge phenomenon occurs during this stage. Simultaneously, a certain phase difference exists between the voltage and current, reflecting the influence of the combined characteristics of surface resistance and capacitance on the leakage current. This diagram verifies that the leakage current during the wetting stage is dominated by a power frequency component with a small DC offset, providing experimental basis for subsequent DC component extraction and content estimation.

[0061] Figure 5 This diagram illustrates the frequency components of the wetting leakage current in an embodiment of the present invention, showing the energy distribution characteristics of the leakage current during the wetting stage in the frequency domain after FFT analysis. As can be seen from the diagram, the signal exhibits a significant DC component peak at 0 Hz and a dominant power frequency component at 50 Hz, with concentrated energy and significant high-frequency attenuation. This indicates that the leakage current during the wetting stage is predominantly a power frequency signal with a small DC offset and extremely weak high-frequency noise components. This result verifies that the wetting leakage current signal extracted in this invention possesses good stability and purity, providing a basis for estimating the DC component content.

[0062] In summary, this invention achieves high-precision simulation and acquisition of insulator leakage current by: constructing a controlled wetting test platform based on the inclined plane method, combining high-sampling-rate data acquisition with multi-sensor synchronous monitoring; employing a multi-dimensional joint identification method involving time-domain threshold segmentation, spectral energy distribution analysis, and dynamic feature matching to accurately separate the arc interval and eliminate interference signals; performing sliding window mid-value filtering on the remaining signal to eliminate baseline drift, extracting pure wetting leakage current, and using FFT analysis to extract the DC component for quantitative estimation of its content. This method achieves high-precision processing throughout the entire process from experimental simulation, signal separation, filtering correction to DC extraction, significantly improving the accuracy of arc identification and the sensitivity of DC component detection, providing a reliable technical means for the quantitative diagnosis of the surface wetting characteristics, contamination level, and aging state of AC insulators.

[0063] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for simulating AC insulator leakage current and extracting DC current, characterized in that: include, An experimental platform was built based on a data acquisition device, an inclined plane method experimental device, and sensors. Leakage current was collected by applying AC voltage under controlled wetting conditions using the inclined plane method, and the collected leakage current signal was processed by moving average filtering. The arc intervals were identified and eliminated by time-domain threshold segmentation, spectral energy distribution analysis and dynamic feature matching. Stable wetting leakage current was extracted after filtering and spectral verification. FFT analysis was performed on the wetting leakage current to extract the DC component and estimate its content.

2. The method for simulating AC insulator leakage current and extracting DC current as described in claim 1, characterized in that: The construction of the test platform includes connecting the data acquisition device to the current sensor to detect weak DC components, and achieving multi-channel synchronous acquisition by connecting multiple sensors to the data acquisition device. The inclined plane test device simulates the wetting process of the insulator surface under controllable conditions. By forming a continuous water film through constant flow of dripping liquid, it reproduces the actual working conditions of leakage current generation and arc discharge, providing a stable and repeatable experimental environment for the acquisition and analysis of leakage current signals.

3. The method for simulating AC insulator leakage current and extracting DC current as described in claim 2, characterized in that: The method of collecting leakage current by inclined plane includes placing an insulator sample on an inclined plane structure, covering the upper electrode with filter paper and connecting it to a peristaltic pump, and having the peristaltic pump drip solution onto the filter paper at a constant flow rate to saturate the filter paper and form a continuous fine stream, simulating the wetting of the insulator surface and forming a leakage circuit; connecting the lower electrode to the insulating material and applying a constant AC voltage between the upper and lower electrodes to form a controlled wetting environment; after applying the voltage, synchronously collecting the leakage current signal and storing the original data; and using a moving average filter to eliminate high-frequency noise and retain low-frequency characteristics.

4. The method for simulating AC insulator leakage current and extracting DC current as described in claim 3, characterized in that: The process of identifying and eliminating arc intervals includes: initially screening arc current intervals using a time-domain threshold segmentation method; continuously monitoring the collected leakage current signal; and marking the sampling time corresponding to the leakage current time series as the arc start point when the current change rate exceeds a preset multiple threshold. The arc start point is used to identify the moment when the current changes abruptly and rises rapidly. in, The rate of change of current; is the threshold coefficient for the rate of change of current, which is a dimensionless coefficient with a value range of 1.5 to 2.5; This is the effective value of the leakage current; When the instantaneous current amplitude gradually decreases from the peak stage of the arc, and satisfies: in, This represents the instantaneous current amplitude. This is the effective value of the leakage current; The amplitude reduction factor is taken as 0.2 to 0.3; The sampling time corresponding to the leakage current time series is marked as the arc termination point, which is used to identify the moment when the current amplitude drops and tends to a steady state. Based on the arc start and end points, the arc segment is accurately extracted from the original leakage current signal, and the arc duration, peak current and energy characteristic parameters are extracted. By setting a minimum duration threshold, short-time noise is eliminated, and the arc current range is effectively identified. The spectral energy distribution analysis to verify the arc characteristics includes performing FFT analysis on the leakage current signal to obtain the power spectral density of each frequency band; calculating the energy proportion of the power spectral density in the high-frequency band from 1 kHz to 50 kHz; when the high-frequency energy proportion is not less than a preset threshold of 10%, and the amplitude of the power frequency component decays to less than 50% relative to the steady-state value, the time period is determined to be the arc interval; based on the determination result of the spectral analysis, the time interval of the arc occurrence is output to provide a basis for subsequent signal rejection and wetting leakage current extraction.

5. The method for simulating AC insulator leakage current and extracting DC current as described in claim 4, characterized in that: The dynamic feature matching includes extracting waveform features, including rise time and fall time, from the obtained arc interval and matching them with a preset template library based on cosine similarity. The preset template library consists of arc current waveform samples collected experimentally and generated by simulation. The samples are normalized and clustered to form multiple representative templates, which are used to determine the arc attributes of candidate signal intervals based on waveform cosine similarity or cross-correlation during the signal recognition stage. When the cosine similarity between the candidate interval waveform and the arc template is not less than 0.8, it is determined to be an arc interval and is eliminated. Based on the determined candidate arc intervals, the synchronization and amplitude consistency of the upper and lower electrode currents are verified by multiple sensors. If the cross-correlation time delay of the upper and lower electrode current signals does not exceed 1 ms according to the time synchronization criterion and the ratio of the peak value or effective value of the upper and lower electrode current signals is in the range of 0.5 to 2.0 according to the amplitude consistency criterion, the candidate interval is confirmed to be an arc interval and is eliminated. Otherwise, it is determined to be a non-arc interference signal and is not eliminated.

6. The method for simulating AC insulator leakage current and extracting DC current as described in claim 5, characterized in that: The wetting leakage current extraction includes: after removing the arc interval, performing a sliding window mid-range filter on the remaining signal to eliminate baseline drift. The width of the sliding window is 50 ms to obtain the wetting leakage current; and performing FFT verification on the wetting leakage current. When the high-frequency energy ratio is less than 5% and the power frequency component amplitude fluctuation does not exceed ±10%, the signal is confirmed to be stable and used as a pure wetting leakage current for subsequent DC component extraction.

7. The method for simulating AC insulator leakage current and extracting DC current as described in claim 6, characterized in that: The extraction and content estimation of the DC component includes performing FFT analysis on the extracted wetting leakage current signal to convert the time-domain signal into a frequency-domain signal and obtain the amplitude distribution of different frequency components; extracting the amplitude of the component corresponding to the frequency of 0 Hz as the amplitude of the DC component, and calculating the proportion of the DC component. in, The percentage of DC component; This represents the amplitude of the DC component. This is the effective value of the current.

8. A system for simulating AC insulator leakage current and extracting DC current, based on the method for simulating AC insulator leakage current and extracting DC current according to any one of claims 1 to 7, characterized in that: Includes an experimental platform construction module: an experimental platform is constructed based on a data acquisition device, an inclined plane method experimental device, and sensors; Signal preprocessing module: The leakage current is collected by applying AC voltage under controlled wetting conditions using the inclined plane method, and the collected leakage current signal is processed by moving average filtering. Arc identification and rejection module: The arc interval is identified and rejected by means of time-domain threshold segmentation, spectrum energy distribution analysis and dynamic feature matching. Stable wetting leakage current is extracted after filtering and spectrum verification. DC component extraction module: Performs FFT analysis on wetting leakage current to extract DC component and estimate its content.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, it implements the steps of the AC insulator leakage current simulation and DC extraction method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps of the AC insulator leakage current simulation and DC extraction method according to any one of claims 1 to 7.

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