Insulator insulation performance degradation analysis method based on electric field change data

Abstract

The invention discloses an insulator insulation performance degradation analysis method based on electric field change data, and the method comprises the following steps: S1, building a standard feature library: obtaining the spatial electric field distribution feature data of an insulator string in a normal state and a plurality of preset degradation working conditions through simulation calculation, and forming the standard feature library; s2, obtaining actually measured data: measuring the space electric field distribution of the insulator string to be detected on site to obtain actually measured electric field data; s3, data preprocessing: processing the actually measured electric field data, and aligning the actually measured electric field data with the feature data in the standard feature library; s4, feature comparison: comparing the preprocessed measured data with feature data in a standard feature library, and calculating similarity; and S5, degradation diagnosis: judging the state of the insulator chain according to a similarity calculation result, and if the insulator chain is judged to be degraded, outputting degradation position and / or type information.

Description

Technical Field

[0001] This invention relates to the field of insulator testing technology, specifically to a method for analyzing the degradation of insulator insulation performance based on electric field change data. Background Technology

[0002] Insulators are critical insulation components of overhead transmission lines. In recent years, line faults caused by insulator quality problems have occurred frequently. Some insulators have inherent defects, which, under the influence of strong lightning currents, may cause insulators to burst and break, leading to line faults and power outages. Zero-value testing of replaced insulators revealed that some porcelain insulators were in a low or zero-value state, and composite insulators had conductivity defects, proving that there were already deteriorated insulators in operation posing a potential operational hazard. However, due to high line loads and short window for line outage maintenance, it is often difficult to thoroughly investigate and eliminate the operational hazards of deteriorated insulators in a short period.

[0003] It is difficult to judge the performance of porcelain and composite insulators by appearance. Therefore, for transmission lines, the main method for monitoring deteriorated insulators is manual inspection. Workers wear conductive shoes and carry insulator testers, insulator operating rods and other tools to climb the towers and inspect all insulators piece by piece (string by string). This method is labor-intensive, inefficient, and expensive, and poses safety hazards such as falls from heights and electric shocks. Moreover, it is susceptible to electromagnetic interference, which can easily lead to false detections or missed detections, causing great trouble for the operation and maintenance of transmission lines. Summary of the Invention

[0004] The purpose of this invention is to provide a method for analyzing the degradation of insulation performance of insulators based on electric field change data, in order to solve the technical problems existing in the background art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for analyzing the insulation performance degradation of insulators based on electric field variation data includes the following steps: S1. Construct a standard feature library: Through simulation calculations, obtain spatial electric field distribution characteristic data of insulator strings under normal conditions and various preset adverse working conditions to form a standard feature library; S2. Obtain measured data: Measure the spatial electric field distribution of the insulator string to be tested in the field to obtain measured electric field data; S3. Data preprocessing: Process the measured electric field data and align it with the feature data in the standard feature library; S4. Feature Comparison: Compare the preprocessed measured data with the feature data in the standard feature library and calculate the similarity. S5. Deterioration Diagnosis: Based on the similarity calculation results, determine the state of the insulator string. If it is determined to be deteriorated, output the deterioration location and / or type information.

[0006] Furthermore, step S1 specifically includes the following steps: S11. Establish a three-dimensional finite element model that includes the target transmission line towers, conductors, and insulator strings; S12. Set the electrical properties and boundary conditions of the model; S13. Simulate and calculate the spatial electric field distribution along the insulator string axis under normal conditions to obtain normal characteristic data; S14. Simulate the degradation of insulators at different locations and / or of different types in the model, and calculate the spatial electric field distribution under each degradation condition to obtain the corresponding degradation characteristic data.

[0007] Furthermore, in step S2, on-site measurements are completed using an electric field sensing module mounted on a drone, helicopter, or ground mobile platform.

[0008] Furthermore, in step S2, the electric field sensing module includes a laser source, a polarization-maintaining fiber, an electric field sensor, a single-mode fiber, and a photodetector. The laser source is used to emit linearly polarized light of a fixed wavelength. The linearly polarized light enters the electric field sensor through the polarization-maintaining fiber. Under the action of the external electric field, the optical power changes. The optical signal output from the electric field sensor is transmitted to the photodetector through the single-mode fiber. The photodetector converts the optical signal into a voltage signal that is proportional to the amplitude of the input optical power.

[0009] Furthermore, the electric field sensor includes a housing, an electro-optic crystal, an optical waveguide, and shielding electrodes; The outer shell is made of polyethylene material, and the electro-optic crystal encased inside the outer shell is made of lithium niobate crystal or bismuth germanate crystal. The optical waveguide is etched inside an electro-optic crystal, and the optical waveguide branches into two paths on the side near the input end. One of the two optical waveguides after the branching is equipped with the shielding electrode, and the two optical waveguides merge into one on the side near the output end.

[0010] Furthermore, the laser and the photodetector are integrated, and the laser is a DFB type laser with a wavelength of 1550nm, and the photodetector is a PIN photodetector.

[0011] Furthermore, in step S4, the method used to calculate the similarity includes Euclidean distance, dynamic time warping algorithm, or Pearson correlation coefficient method.

[0012] Further, in step S5, determining the state of the insulator string specifically involves: If the similarity between the measured data and the normal feature data is the highest and exceeds the first threshold, then the state is determined to be normal. If the measured data has the highest similarity to a certain degradation feature data and exceeds the second threshold, degradation is determined, and the location and / or type of degradation are determined based on the working condition information corresponding to the degradation feature data.

[0013] Furthermore, in step S5, if the highest similarity between the measured data and all feature data in the standard feature library is lower than the second threshold, a diagnostic uncertainty prompt is output.

[0014] Furthermore, after step S5, the following step is also included: S6. Visualize the comparison chart of diagnostic results, measured data and matched feature data.

[0015] Compared with the prior art, the advantages of the present invention are as follows: The insulator insulation performance degradation analysis method based on electric field change data provided by this invention has high diagnostic accuracy and precise location. It establishes a standard feature library based on precise three-dimensional finite element simulation, fully considering the complex influence of actual structures such as towers and conductors on the electric field, making the diagnostic basis more scientific and accurate. By comparing with the characteristic curves of deterioration conditions at different locations, it can directly locate which insulator(s) have deteriorated, providing a clear target for maintenance. Furthermore, the method is extremely sensitive to changes in insulation resistance due to electric field changes, capturing weak electric field distortions caused by early degradation and achieving early warning. The entire analysis process is automatically completed by the algorithm, eliminating the need for manual interpretation of complex electric field spectra, reducing human error, improving analysis efficiency, and demonstrating strong applicability. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this embodiment, the accompanying drawings used in the description of the embodiment will be briefly introduced below. 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.

[0017] Figure 1 This is a flowchart illustrating a method for analyzing the degradation of insulation performance of insulators based on electric field change data, provided by the present invention. Figure 2 This is a schematic diagram of the electric field simulation of the conductivity defect of the composite insulator in a specific embodiment; Figure 3 This is a schematic diagram of the electric field sensing module; Figure 4 This is a schematic diagram of an electric field sensor. Detailed Implementation

[0018] To make the technical means, creative features, objectives and effects of this invention easier to understand, the following description, in conjunction with the accompanying drawings and specific embodiments, further explains how this invention is implemented.

[0019] In one specific embodiment, refer to Figure 1 As shown, this invention provides a method for analyzing the insulation performance degradation of insulators based on electric field change data, comprising the following steps: S1. Constructing a Standard Feature Library: Through simulation calculations, obtain spatial electric field distribution characteristic data of insulator strings under normal conditions and various preset adverse working conditions, forming a standard feature library. Step S1 specifically includes the following steps: S11. Establish a three-dimensional finite element model that includes the target transmission line towers, conductors, and insulator strings.

[0020] Reference Figure 2 As shown, in a specific embodiment, an overall model of the composite insulator string and equalizing ring can be established for electric field simulation analysis of a 500kV composite insulator. The inner air domain is 2.8m long, 2.8m wide, and 10m high; the outer air domain is 5m long, 3m wide, and 15m high; the outer ring of the metal ring electrode has a radius of 700mm, and the inner ring has a radius of 300mm; the overall height of the insulator string is 4185mm, the fittings are 73mm long and have a radius of 30mm; the diameter of the first shed is 300mm, the diameter of the large shed below the first shed is 180mm, and the diameter of the small shed is 150mm; conductivity defects of the sheds at different locations are set based on historical data. In this way, the insulator electric field feature library is constructed.

[0021] S12. Set the electrical properties and boundary conditions of the model.

[0022] S13. Simulate and calculate the spatial electric field distribution along the insulator string axis under normal conditions to obtain normal characteristic data.

[0023] S14. Simulate the degradation of insulators at different locations and / or of different types in the model, and calculate the spatial electric field distribution under each degradation condition to obtain the corresponding degradation characteristic data.

[0024] S2. Obtain measured data: Measure the spatial electric field distribution of the insulator string to be tested in the field to obtain measured electric field data.

[0025] Field measurements can be performed using electric field sensing modules mounted on drones, helicopters, or ground mobile platforms.

[0026] Preferably, refer to Figure 3As shown, the electric field sensing module includes a laser 1, a polarization-maintaining fiber 2, an electric field sensor 3, a single-mode fiber 4, and a photodetector 5. The laser 1 emits linearly polarized light of a fixed wavelength. This linearly polarized light passes through the polarization-maintaining fiber 2 and enters the electric field sensor 3. Under the influence of an external electric field, the optical power changes. The optical signal output from the electric field sensor 3 is transmitted to the photodetector 5 via the single-mode fiber 4. The photodetector 5 converts the optical signal into a voltage signal proportional to the amplitude of the input optical power. The entire system exhibits strong reproducibility of electric field signals. The detection frequency is 0-5 kHz, and the electric field strength measurement range is 20 kV / m-3000 kV / m.

[0027] In this embodiment, the laser and the photodetector are integrated, and the laser is a DFB type laser with a wavelength of 1550nm, and the photodetector is a PIN photodetector.

[0028] Further reference Figure 4 As shown, the electric field sensor 3 includes a housing, an electro-optic crystal 6, an optical waveguide 7, and a shielding electrode 8. The housing is made of polyethylene material, and the electro-optic crystal 6 encased inside the housing is made of lithium niobate crystal or bismuth germanate crystal. The optical waveguide 7 is etched inside the electro-optic crystal 6, and the optical waveguide branches into two paths on the side near the input end. One of the two optical waveguides after the branching is covered with a shielding electrode 8 made of metal material, and the two optical waveguides merge into one on the side near the output end.

[0029] The principle of traditional capacitive electric field sensors is that induced charges are generated on the sensor surface under alternating electric fields. When a capacitor is connected between the sensor's electrodes, the capacitor generates a voltage, and the magnitude of the electric field can be deduced from the voltage. Spherical capacitive electric field sensors are relatively simple to manufacture and inexpensive. However, in practical applications, spherical electric field sensors have low measurement accuracy, mainly due to their large probe size (approaching several meters in length to increase sensitivity) and the fact that they are often made of metal. This results in significant distortion of the electric field in the measured area, especially when measuring low-frequency and electrostatic fields, where insufficient energy is often obtained, leading to large measurement errors.

[0030] Therefore, this invention employs a photoelectric sensor based on the electro-optic effect, also known as the Pockels effect, which refers to the proportionality between the change in refractive index and the applied electric field strength. Utilizing the characteristic that the refractive index of an electro-optic crystal changes under an applied electric field strength in a certain direction, the spatial field strength signal is converted into an optical power signal for transmission. Then, a photoelectric converter converts the optical power signal into a voltage signal, enabling transient measurement of the external electric field. Its measurement circuit is completely isolated from the high-voltage circuit, exhibiting strong anti-interference capabilities and good transient response. When the input optical power is constant, the output optical power is a sinusoidal function of the applied electric field, thus the output optical power can be approximated as a linear function of the external field strength. In this way, by detecting the optical power of the electric field sensor, the magnitude of the external electric field can be determined.

[0031] In this embodiment, the overall dimensions of the electric field sensor housing are 55*8*4mm, the encased electro-optic crystal is 40*4*1mm in size, the optical waveguide etched on the electro-optic crystal is 30mm long, and the shielding electrode laid on one of the optical waveguide arms is 20mm long. Its small overall size makes it suitable for use on drones.

[0032] S3. Data preprocessing: The measured electric field data is processed and aligned with the feature data in the standard feature library.

[0033] S4. Feature Comparison: Compare the preprocessed measured data with the feature data in the standard feature library and calculate the similarity.

[0034] The methods used to calculate similarity include Euclidean distance, dynamic time warping algorithm, or Pearson correlation coefficient method.

[0035] S5. Deterioration Diagnosis: Based on the similarity calculation results, determine the state of the insulator string. If it is determined to be deteriorated, output the deterioration location and / or type information.

[0036] The specific steps to determine the state of an insulator string are as follows: If the similarity between the measured data and the normal feature data is the highest and exceeds the first threshold, then the state is determined to be normal. If the measured data has the highest similarity to a certain degradation feature data and exceeds the second threshold, degradation is determined to exist, and the degradation location and / or type is determined based on the working condition information corresponding to the degradation feature data. If the highest similarity between the measured data and all feature data in the standard feature library is lower than the second threshold, a diagnostic uncertainty message will be output.

[0037] S6. Visualize the comparison chart of diagnostic results, measured data and matched feature data.

[0038] In summary, the insulator insulation performance degradation analysis method based on electric field change data provided by this invention has high diagnostic accuracy and precise location. It establishes a standard feature library based on precise three-dimensional finite element simulation, fully considering the complex influence of actual structures such as towers and conductors on the electric field, making the diagnostic basis more scientific and accurate. By comparing with the characteristic curves of deterioration conditions at different locations, it can directly locate which insulator(s) has deteriorated, providing a clear target for maintenance. Furthermore, the electric field change is extremely sensitive to changes in insulation resistance, enabling the detection of weak electric field distortions caused by early degradation, achieving early warning. The entire analysis process is automatically completed by the algorithm, eliminating the need for manual interpretation of complex electric field spectra, reducing human error, improving analysis efficiency, and demonstrating strong applicability.

[0039] Finally, it should be noted that the above description is only an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for analyzing deterioration of an insulating performance of an insulator based on electric field change data, characterized by, The method comprises the following steps: S1, constructing a standard feature library: through simulation calculation, obtaining spatial electric field distribution feature data of insulator strings under normal state and various preset degradation conditions, forming a standard feature library; S2, obtaining measured data: measuring the spatial electric field distribution of the insulator string to be detected in the field to obtain measured electric field data; S3, data preprocessing: processing the measured electric field data and aligning it with the feature data in the standard feature library; S4, feature comparison: comparing the preprocessed measured data with the feature data in the standard feature library to calculate the similarity; S5, degradation diagnosis: judging the state of the insulator string according to the similarity calculation result, and if it is determined to be degraded, outputting the degradation position and / or type information.

2. The electric field change data-based insulator performance degradation analysis method for an insulator according to claim 1, characterized by, In step S1, the following steps are specifically included: S11, establishing a three-dimensional finite element model containing the target transmission line tower, conductor and insulator string; S12, setting the electrical properties and boundary conditions of the model; S13, simulating and calculating the spatial electric field distribution along the axis of the insulator string under normal state to obtain normal feature data; S14, simulating different positions and / or types of insulator degradation in the model, and respectively simulating and calculating the spatial electric field distribution under each degradation condition to obtain corresponding degradation feature data.

3. The method of claim 1, wherein the method is characterized by: In step S2, the field measurement is completed by an electric field sensing module mounted on a UAV, helicopter or ground mobile platform.

4. The electric field change data-based insulator performance degradation analysis method of claim 3, wherein In step S2, the electric field sensing module includes a laser source, a polarization maintaining optical fiber, an electric field sensor, a single-mode optical fiber and a light detector; The laser source is used to emit linearly polarized light of a fixed wavelength. The linearly polarized light enters the electric field sensor through the polarization maintaining optical fiber. Under the action of the external electric field, the optical power changes. The optical signal output from the electric field sensor is transmitted to the light detector through the single-mode optical fiber. The light detector converts the optical signal into a voltage signal proportional to the input optical power amplitude.

5. The UAV based non-contact overhead line insulator degradation detection system as claimed in claim 4, wherein The electric field sensor includes a shell, an electro-optic crystal, an optical waveguide and a shielding electrode; The shell is made of polyethylene material, and the electro-optic crystal wrapped inside the shell is made of lithium niobate crystal or bismuth germanate crystal; The optical waveguide is engraved inside the electro-optic crystal, and one side of the optical waveguide near the input end is bifurcated into two paths. One of the two bifurcated optical waveguides is provided with the shielding electrode, and the two bifurcated optical waveguides are combined into one at the side near the output end.

6. The UAV based non-contact overhead line insulator degradation detection system as claimed in claim 5, wherein The laser and the light detector are integrally arranged, and the laser is a DFB type laser with a wavelength of 1550 nm. The light detector is a PIN light detector.

7. The method of claim 1, wherein the method is characterized by: In step S4, the method for calculating the similarity includes the Euclidean distance method, the dynamic time warping algorithm or the Pearson correlation coefficient method.

8. The method of claim 1, wherein the method is characterized by: In step S5, the judgment of the state of the insulator string is specifically: If the similarity between the measured data and the normal feature data is the highest and exceeds the first threshold value, it is determined that the state is normal; If the similarity between the measured data and a certain degradation feature data is the highest and exceeds the second threshold value, it is determined that there is degradation, and the degradation position and / or type is determined according to the working condition information corresponding to the degradation feature data.

9. The electric field change data-based insulator performance degradation analysis method for an insulator according to claim 8, characterized by, In step S5, if the highest similarity between the measured data and all feature data in the standard feature library is lower than the second threshold, a prompt of uncertain diagnosis is outputted.

10. The method of claim 1, wherein the method is characterized by: After step S5, the following step is further included: S6, visualizing display of the diagnosis result and a comparison chart between the measured data and the matched feature data.

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