Oil paper insulation aging state diagnosis method and device based on depolarization current curve

Abstract

The invention provides an oil paper insulation aging state diagnosis method and device based on a depolarization current curve, and relates to the technical field of oil paper insulation equipment state diagnosis. According to the method, depolarization current curves at different discharge times are obtained, and a reference curve is selected; a certain current value of the reference curve is selected as a base point, and a double-time translation factor is calculated; according to the double-time translation factor, mapping the depolarization current curves at different discharge times to a reference curve to obtain a translation normalized curve; identifying an interfered curve and an uninterfered area and an interfered area thereof according to the translation normalized curve; de-noising an interfered area of each translation normalized curve by taking the reference curve as a reference, and forming a de-noised curve by a de-noised result and an uninterfered area; and diagnosing the oil paper insulation aging state based on the de-noising curve to obtain a diagnosis result. The influence of test conditions such as discharge time is considered, and the diagnosis efficiency of the oil paper insulation aging state is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil-paper insulation equipment state diagnosis, in particular to an oil-paper insulation aging state diagnosis method and device based on a depolarization current curve. BACKGROUND

[0002] Oil-paper insulation equipment is a core component of a power system, and its aging state is directly related to the safety and stability of power grid operation, so it is crucial to accurately diagnose its aging. As a non-destructive and highly sensitive diagnosis technology, the depolarization current method has become an important means of oil-paper insulation aging analysis. The depolarization current curve obtained by testing can construct aging characteristic quantities and an extended Debye equivalent circuit, providing a key basis for aging state evaluation.

[0003] However, the existing diagnosis scheme based on the depolarization current method has significant limitations: first, the depolarization current curve test is significantly affected by the discharge time, and the curves of the same insulation medium under different discharge times differ greatly, and the most suitable discharge time for representing the aging state has not been determined, so directly using the test curve for evaluation lacks scientificity; second, the difference in discharge time will cause deviations in aging characteristic quantities and equivalent circuit parameters, resulting in inconsistent evaluation results; third, the test is easily disturbed by environmental noise, and such disturbances do not cause curve mutations, making them difficult to identify, which affects the reliability of subsequent aging analysis due to test errors. These problems restrict the popularization and application of the depolarization current method in field diagnosis.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] The present application aims to provide an oil-paper insulation aging state diagnosis method and device based on a depolarization current curve to solve the problem that the existing method does not consider the influence of test conditions (such as test voltage, discharge time, environmental factors, etc.) on the evaluation results of oil-paper insulation aging state.

[0006] To solve the above technical problems, the present application realizes the following technical scheme: An oil-paper insulation aging state diagnosis method based on a depolarization current curve, comprising: S1, obtaining depolarization current curves under different discharge times, and selecting a depolarization current curve corresponding to a certain discharge time as a reference curve; S2, selecting a certain current value of the reference curve as a base point, and calculating double-time translation factors of depolarization current curves under other discharge times; S3, mapping the depolarization current curves under different discharge times to the reference curve according to the calculated double-time translation factors to obtain a translation normalized curve; S4. Identify the disturbed curve and its undisturbed and disturbed regions based on the translation normalization curve. S5. Using the reference curve as a reference, the disturbed area of ​​each translation normalization curve is denoised, and the denoised result is combined with the undisturbed area to form a denoised curve. S6. Based on the noise reduction curve, the aging state of the oil paper insulation is diagnosed, and the diagnosis result is obtained.

[0007] Preferably, the depolarization current curve is obtained in the following manner: For the same paper insulation sample, under the same test voltage and the same ambient temperature, the test was performed. The depolarization current curves corresponding to different discharge times are denoted as follows: , This is the depolarization time.

[0008] Preferably, S2 specifically comprises: In the reference curve A stable current value is selected as the base point, and the corresponding depolarization time is... ; Based on depolarization current curve Find the depolarization time corresponding to the current value closest to the base point. The dual-time translation factor is calculated, and its expression is as follows: ; in, Depolarization current curve At the point of time The two-time translation factor; For the first Depolarization current curve; This is the depolarization time.

[0009] Preferably, S3 specifically comprises: The first depolarization current curve The time axis is adjusted to align with the reference curve. Alignment, according to the dual time translation factor The current value corresponding to each time point of the depolarization current curve after translation and normalization is calculated to obtain the translation and normalization curve.

[0010] Preferably, S4 specifically comprises: Calculate the relative current deviations of all translation-normalized curves from the reference curve: ; in, For the j-th translational normalized curve a current relative deviation; a deviation threshold value a coincidence proportion threshold value and a sliding window length L; a proportion of an area in which the current relative deviation of a curve other than the reference curve is less than the deviation threshold value ; if the proportion of the area is less than the coincidence proportion threshold value , the coincidence degree of most of the translation normalized curves with the reference curve is low, and the current relative deviation between the translation normalized curves is less than , most of the translation normalized curves coincide with each other, and the reference curve is an interference curve; a curve with the minimum current relative deviation is selected from the coincident translation normalized curves as the final reference curve; if the proportion of the area reaches the coincidence proportion threshold value , the coincidence degree of most of the translation normalized curves with the reference curve is high, and the reference curve is retained as the final reference curve; based on the final reference curve, the current relative deviation with other translation normalized curves is recalculated, that is, a new current relative deviation , and a sliding window with a length of L is used to traverse each translation normalized curve; if there are k consecutive windows of exceeding in the current traversed curve , the current traversed curve is an interference curve, and an interference area is marked.

[0011] Preferably, S5 is specifically: According to the double-time translation factor, the reference current value corresponding to the interference area in each interference curve is inversely calculated and replaced with the reference curve as the reference, and then spliced with the non-interference area to obtain a denoising curve.

[0012] The application also provides an oil-paper insulation aging state diagnosis device based on a depolarization current curve, comprising: a reference curve unit configured to obtain depolarization current curves under different discharge times, and select a depolarization current curve corresponding to a certain discharge time as a reference curve; a double-time translation factor unit configured to select a certain current value of the reference curve as a base point, and calculate double-time translation factors of depolarization current curves under other discharge times; a translation normalization unit configured to map the depolarization current curves under different discharge times to the reference curve according to the calculated double-time translation factors, and obtain translation normalized curves; An interference identification unit is configured to identify an interference curve and an interference-free region and an interference region of the interference curve according to the translation normalized curve; A denoising unit is configured to denoise the interference region of each translation normalized curve based on the reference curve, and combine the denoised result with the interference-free region to obtain a denoised curve. A diagnosis unit is configured to diagnose the oil-paper insulation aging state based on the denoised curve to obtain a diagnosis result.

[0013] The application further provides an oil-paper insulation aging state diagnosis device based on a depolarization current curve, which comprises a processor and a memory, and the memory stores a computer program which can be executed by the processor to implement the oil-paper insulation aging state diagnosis method based on the depolarization current curve.

[0014] The application further provides a computer readable storage medium, which stores computer readable instructions, and the computer readable instructions are executed by a processor of a device where the computer readable storage medium is located to implement the oil-paper insulation aging state diagnosis method based on the depolarization current curve.

[0015] In summary, compared with the prior art, the application has the following beneficial effects: The application can translate and normalize the depolarization current curves under different discharge times, eliminate the influence of discharge time on the subsequent evaluation of the oil-paper insulation aging state by using the depolarization current aging characteristic quantity, and facilitate the popularization and application of the depolarization current diagnosis method in field testing and aging diagnosis.

[0016] The depolarization current curve interfered by noise and other environmental factors often has a similar decay trend to the depolarization current without interference, and cannot be visually distinguished. The application can effectively solve the problem that the traditional method cannot identify and quantify the interference by calculating and comparing the current relative deviation, and facilitate the reliability of the subsequent evaluation of the oil-paper insulation aging state based on the depolarization current aging characteristic quantity and the construction of equivalent circuit parameters.

[0017] The application can reliably eliminate the depolarization current test error caused by environmental noise and other factors by denoising operation, restore the true undisturbed test value, not only reduce the redundancy of the depolarization current test data, improve the test efficiency of the depolarization current, but also further improve the reliability of the subsequent evaluation of the oil-paper insulation aging state based on the depolarization current aging characteristic quantity and the construction of equivalent circuit parameters. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as limiting the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0019] Figure 1 A flowchart of an oil-paper insulation aging state diagnosis method based on depolarization current curve provided for example one.

[0020] Figure 2 A depolarization current curve diagram under different discharge times provided for example one.

[0021] Figure 3 A depolarization current curve translation normalization effect diagram provided for example one.

[0022] Figure 4 A comparison effect diagram of depolarization current curves with and without interference provided for example one.

[0023] Figure 5 An effect diagram of interference curve processed by translation normalization method provided for example one.

[0024] Figure 6 A denoising effect diagram provided for example one.

[0025] Figure 7 A schematic diagram of an oil-paper insulation aging state diagnosis device based on depolarization current curve provided for example two.

[0026] The present application will be further described in detail below in conjunction with the drawings and specific embodiments. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0028] Example one Embodiment 1 of the present invention provides a method for diagnosing the aging state of oil-paper insulation based on depolarization current curves, which can be implemented by an oil-paper insulation aging state diagnosis device based on depolarization current curves (hereinafter referred to as the diagnosis device), specifically, executed by one or more processors within the diagnosis device.

[0029] In this embodiment, the diagnostic device may be an electronic device equipped with a processor, which carries a computer program for the diagnostic method of oil-paper insulation aging state based on depolarization current curve and the computer program can be executed, such as a computer, smartphone, smart tablet, workstation, etc., which are not limited here.

[0030] like Figure 1 As shown, a method for diagnosing the aging state of oil-paper insulation based on depolarization current curves includes steps S1 to S6.

[0031] S1. Obtain the depolarization current curves at different discharge times, and select the depolarization current curve corresponding to a certain discharge time as the reference curve.

[0032] The purpose of this step is to determine the normalization reference benchmark, which lays the foundation for subsequent deviation determination.

[0033] In practice, a depolarization current testing device (such as a dielectric loss tester) is used to test the same oil-paper insulation sample under the same test voltage and ambient temperature. The depolarization current curves corresponding to different discharge times are denoted as follows: , This is the depolarization time. Let be the current value of the j-th curve at time t.

[0034] A baseline curve can be initially selected based on the discharge time being moderate and the curve showing no significant fluctuations. .

[0035] like Figure 2 The four depolarization current curves shown are for different discharge times: 150s (curve 1), 225s (curve 21), 375s (curve 3, set as the reference curve), and 500s (curve 4).

[0036] S2, select a certain current value of the reference curve as the base point, and calculate the dual-time shift factor of the depolarization current curve for other discharge times.

[0037] Based on the consistency of the depolarization attenuation law of the same insulation sample, the time shift is determined by matching the current value, and the "time-current" correspondence between different discharge time curves and the reference curve is quantified, providing a basis for shift normalization.

[0038] In the reference curve A stable current value is selected as the base point, and the corresponding depolarization time is... ; Based on depolarization current curve Find the depolarization time corresponding to the current value closest to the base point. The dual-time translation factor is calculated, and its expression is as follows: ; in, Depolarization current curve At the point of time The two-time translation factor; For the first Depolarization current curve; This is the depolarization time.

[0039] S3. Based on the calculated dual-time translation factor, the depolarization current curves at different discharge times are mapped to the reference curve to obtain the translation normalized curve.

[0040] In this step, different discharge time curves are mapped to the "time-current" space of the reference curve to eliminate the influence of discharge time and obtain a set of shifted and normalized curves.

[0041] Specifically, the first depolarization current curve The time axis is adjusted to align with the reference curve. Alignment, according to the dual time translation factor The current value corresponding to each time point of the depolarization current curve after translation and normalization is calculated to obtain the translation and normalization curve.

[0042] like Figure 3 The diagram shows the translation effect of the four depolarization current curves, with a current value of 10. -6 Using the reference point as the baseline, the time-shift factors for curves 1, 2, and 4 were calculated to be 1.20, 1.10, and 0.96, respectively. After translation and normalization, curves 1, 2, and 4 all exhibit highly consistent distribution characteristics with the reference curve 3 in the measurement time domain; on the exponential time axis, it is clearly observable that each curve forms a cluster of curves with a high degree of consistency. The formation of this curve cluster eliminates most of the response differences caused by different discharge times, enhancing the comparability between different test data.

[0043] S4. Identify the disturbed curve and its undisturbed and disturbed regions based on the translational normalization curve.

[0044] The purpose of this step is to accurately locate the disturbed curve (including the reference curve) and the disturbed region by combining the "deviation rule between the reference and translation normalized curves". If the reference curve deviates significantly from other translation normalized curves in some regions, and the other translation normalized curves basically overlap, then the reference curve is the disturbed curve; If the overlap ratio between the baseline curve and the translational normalized curve exceeds a set threshold (e.g., 80%), and only a few individual curves deviate significantly in certain regions, then these individual curves are considered disturbed curves.

[0045] Specifically, the relative current deviations of all translation-normalized curves from the reference curve are calculated: ; in, For the j-th translational normalized curve The relative deviation of the current; Set deviation threshold Overlap ratio threshold With the sliding window length L; The statistics show the percentage of regions in which the relative current deviation is less than a set deviation threshold in other shifted normalized curves besides the aforementioned baseline curve. ; If the regional proportion Less than the overlap ratio threshold Therefore, most of the shifted normalized curves have low overlap with the reference curve, and the relative current deviation between each pair of shifted normalized curves is low. Less than If most of the translational normalized curves overlap, the reference curve is the disturbed curve; from the overlapping translational normalized curves, the curve with the smallest relative current deviation is selected as the final reference curve. If the regional proportion Reaching the overlap ratio threshold If most of the translational normalized curves have a high degree of overlap with the reference curve, then the reference curve is retained as the final reference curve. Based on the final baseline curve, the relative deviation of the current from other shifted normalized curves is recalculated, i.e., the new relative current deviation. And use a sliding window of length L to traverse each translation-normalized curve; if the currently traversed curve has k consecutive windows... Exceed If the current traversed curve is the disturbed curve, the disturbed area will be marked, and the rest will be the undisturbed area.

[0046] Assuming curve 4 is the disturbed curve and the other three curves are undisturbed curves, then curve 3 is taken as the baseline curve. The comparison graph between curve 4 (the disturbed curve) and curve 3 (the baseline curve) is as follows.Figure 4 As shown. From Figure 4 It is known that the gradual change characteristics of the depolarization current curve caused by environmental factors such as noise are often masked by the overall smoothness of the curve, making it difficult to visually distinguish whether it has been disturbed. This leads researchers to treat disturbed depolarization current as reliable data for analyzing the aging state of transformer oil-paper insulation, resulting in misjudgments of its aging condition.

[0047] like Figure 5 As shown, this is a comparison of curves 1, 2, and 4 before and after translation and normalization, using curve 3 as the baseline curve. From... Figure 5 It can be seen that before the translation and normalization method proposed in this invention was applied to curves 1, 2, 3 and 4, their current values ​​showed similar decay trends, and in particular, there were almost no obvious fluctuations visually, making it difficult to identify whether they were disturbed.

[0048] After being processed by the translation normalization method, curves 1, 2, and 4 show that curves 1 and 2 can basically coincide with the reference curve 3, while curve 4 is at 10... 2 ~10 4 The s interval showed a significant deviation, and its curve trend differed significantly from the other three curves. Thus, curve 4 can be clearly identified as an interference curve, which is consistent with the actual situation. This effectively verifies that the translation normalization method proposed in this patent can not only normalize the depolarization current measurement results under different discharge times.

[0049] S5. Using the reference curve as a reference, denoise the disturbed area of ​​each translational normalized curve, and combine the denoised result with the undisturbed area to form a denoised curve.

[0050] The purpose of this step is to eliminate noise in the interference area and restore the true current value as much as possible. If the reference curve is disturbed, the reference will be updated synchronously.

[0051] Based on the dual-time shift factor, using the reference curve as a reference, the reference current value corresponding to the time point of the interference region in each interference curve is calculated and replaced. Then, it is spliced ​​with the uninterrupted region to obtain the denoised curve.

[0052] Alternatively, when calculating the corresponding reference current value, the moving average filter value of several consecutive reference current values ​​can be used for replacement.

[0053] In a preferred embodiment, Figure 5 Taking the baseline curve 3, the disturbed curve 4, and the undisturbed curve 4 as examples, a denoising study of the disturbed curve is conducted. The denoising effect of curve 4 is as follows: Figure 6 As shown.

[0054] Depend on Figure 6It can be seen that the denoised curve 4 and the original disturbed curve 4 are in the range of 10. 2 ~10 4 There are significant differences in the s interval, and the translational normalized curve of the denoised curve 4 basically coincides with the reference curve 3. The denoised curve 4 also basically coincides with the original interference-free curve 4, which verifies the effectiveness of the denoising method for the disturbed depolarization current curve proposed in this patent.

[0055] S6. Based on the noise reduction curve, the aging state of the oil paper insulation is diagnosed, and the diagnosis result is obtained.

[0056] In this step, the aging characteristic quantity and extended Debye equivalent circuit parameters can be extracted based on the denoising curve to determine the aging level (such as mild aging, moderate aging, and severe aging).

[0057] Alternatively, the denoised curve can be input into a pre-trained diagnostic model for the aging state of oil-paper insulation to obtain diagnostic results.

[0058] In summary, compared with the prior art, the present invention has the following beneficial effects: This invention eliminates the interference of discharge time on evaluation results, improving the diagnostic versatility and persuasiveness. One of the core pain points of existing technologies is that "the depolarization current curves under different discharge times vary greatly, and there is no unified reference standard," directly leading to a lack of consistency and scientific validity in curve-based aging evaluation results. This method, through dual-time translation factor calculation and translation normalization design, maps curves of different discharge times to a unified reference curve space, ensuring that the current magnitude and attenuation trend of the curves after translation normalization are highly consistent with the reference curve. It does not rely on "specific discharge times" and can adapt to test data under any discharge time, solving the industry problem of "which discharge time curve is more suitable for characterizing the aging state." This makes the evaluation results no longer affected by the test time, significantly improving the versatility of the diagnostic method in field testing, providing a unified standard for aging evaluation of oil-paper insulation in different scenarios, and enhancing the persuasiveness of the results.

[0059] This invention can accurately identify interfered curves (including baseline curves), avoiding misleading diagnosis with erroneous data. Existing technologies cannot effectively determine whether the depolarization current curve is affected by environmental noise, especially when interference does not cause abrupt changes in the curve, easily leading to erroneous data being used in aging analysis and causing assessment bias. This method overcomes this limitation by identifying interference (including baseline deviation determination) and innovatively designs a "dual determination rule": it can identify both "deviations of individual curves from the baseline" (when most curves overlap, individual curves are interfered with) and "interference of the baseline curve itself" (when most curves overlap but deviate from the baseline, the baseline is interfered with), filling the gap in existing technologies that "cannot verify the validity of the baseline." Combining relative deviation, overlap ratio, and sliding window quantitative determination methods avoids subjective judgment errors, accurately locates interference areas, and ensures that subsequent diagnosis is based only on "uninterrupted or corrected curves," reducing the misleading impact of erroneous data on aging assessment from the source and improving diagnostic reliability.

[0060] This invention efficiently denoises and restores true data, reducing redundancy and improving evaluation accuracy. Existing technologies, when faced with environmental noise interference, either fail to identify the interference or directly discard the interfered curves, leading to redundant test data (requiring repeated testing) or wasted valuable data. This method achieves "precise repair of interference areas" through targeted denoising: for interfered areas, the interference data is replaced with an "interference-free baseline curve" as a reference; uninterrupted areas retain the original normalized data, avoiding curve distortion caused by over-processing. This restores the true depolarization current characteristics without requiring repeated testing, reducing data redundancy and improving testing efficiency. The repaired curves more accurately reflect the polarization characteristics of the oil-paper insulation, providing a high-quality data foundation for subsequent aging characteristic extraction and extended Debye equivalent circuit fitting, further improving the accuracy of aging level determination.

[0061] This invention optimizes aging diagnosis logic, balancing technical rigor with engineering practicality. Existing technologies rely solely on "directly extracting features from the original curve," neglecting data validity and consistency, resulting in poor diagnostic stability. This method achieves a balance between technical rigor and engineering practicality through a closed-loop process of "normalization → interference identification → noise reduction → diagnosis."

[0062] Example 2 like Figure 7 As shown, the second embodiment of the present invention also provides a diagnostic device for the aging state of oil-paper insulation based on the depolarization current curve, comprising: The reference curve unit is used to obtain the depolarization current curves at different discharge times, and select the depolarization current curve corresponding to a certain discharge time as the reference curve. The dual-time shift factor unit is used to select a certain current value of the reference curve as the base point and calculate the dual-time shift factor of the depolarization current curve at other discharge times. The translation normalization unit is used to map the depolarization current curves at different discharge times to the reference curve based on the calculated dual-time translation factor, so as to obtain the translation normalization curve. An interference identification unit is used to identify the interfered curve and its undisturbed and interfered regions based on the translational normalization curve. The denoising unit is used to denoise the disturbed area of ​​each translation normalized curve based on the reference curve, and to combine the denoised result with the undisturbed area to form a denoised curve. The diagnostic unit is used to diagnose the aging state of the oil-paper insulation based on the noise reduction curve and obtain the diagnostic results.

[0063] Example 3 The third embodiment of the present invention also provides a diagnostic device for the aging state of oil-paper insulation based on the depolarization current curve, which includes a memory and a processor. The memory stores a computer program, which can be executed by the processor to realize the aging state diagnostic method for oil-paper insulation based on the depolarization current curve as described above.

[0064] Example 4 The fourth embodiment of the present invention also provides a computer-readable storage medium storing computer-readable instructions. When the computer-readable instructions are executed by the processor of the device where the computer-readable storage medium is located, they implement the above-described method for diagnosing the aging state of oil-paper insulation based on the depolarization current curve.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for diagnosing the aging state of oil-paper insulation based on depolarization current curves, characterized in that, include: S1. Obtain the depolarization current curves at different discharge times, and select the depolarization current curve corresponding to a certain discharge time as the reference curve. S2, Select a current value of the reference curve as the base point, and calculate the dual-time shift factor of the depolarization current curve at other discharge times; S3. Based on the calculated dual-time translation factor, the depolarization current curves at different discharge times are mapped to the reference curve to obtain the translation normalized curve. S4. Identify the disturbed curve and its undisturbed and disturbed regions based on the translation normalization curve. S5. Using the reference curve as a reference, the disturbed area of ​​each translation normalization curve is denoised, and the denoised result is combined with the undisturbed area to form a denoised curve. S6. Based on the noise reduction curve, the aging state of the oil paper insulation is diagnosed, and the diagnosis result is obtained.

2. The method for diagnosing the aging state of oil-paper insulation based on depolarization current curves according to claim 1, characterized in that... The depolarization current curve was obtained in the following way: For the same paper insulation sample, under the same test voltage and the same ambient temperature, the test was performed. The depolarization current curves corresponding to different discharge times are denoted as follows: , This is the depolarization time.

3. The method for diagnosing the aging state of oil-paper insulation based on depolarization current curves according to claim 1, characterized in that... S2 specifically refers to: In the reference curve A stable current value is selected as the base point, and the corresponding depolarization time is... ; Based on depolarization current curve Find the depolarization time corresponding to the current value closest to the base point. The dual-time translation factor is calculated, and its expression is as follows: ； in, Depolarization current curve At the point of time The two-time translation factor; For the first Depolarization current curve; This is the depolarization time.

4. The method for diagnosing the aging state of oil-paper insulation based on depolarization current curves according to claim 3, characterized in that... S3 specifically refers to: The first depolarization current curve The time axis is adjusted to align with the reference curve. Alignment, according to the dual time translation factor The current value corresponding to each time point of the depolarization current curve after translation and normalization is calculated to obtain the translation and normalization curve.

5. The method for diagnosing the aging state of oil-paper insulation based on depolarization current curves according to claim 3, characterized in that... S4 specifically refers to: Calculate the relative current deviations of all translation-normalized curves from the reference curve: ； in, For the j-th translational normalized curve The relative deviation of the current; Set deviation threshold Overlap ratio threshold With the sliding window length L; The statistics show the percentage of regions in which the relative current deviation is less than a set deviation threshold in other shifted normalized curves besides the aforementioned baseline curve. ; If the regional proportion Less than the overlap ratio threshold Therefore, most of the shifted normalized curves have low overlap with the reference curve, and the relative current deviation between each pair of shifted normalized curves is low. Less than If most of the translational normalized curves overlap, the reference curve is the disturbed curve; from the overlapping translational normalized curves, the curve with the smallest relative current deviation is selected as the final reference curve. If the regional proportion Reaching the overlap ratio threshold If most of the translational normalized curves have a high degree of overlap with the reference curve, then the reference curve is retained as the final reference curve. Based on the final baseline curve, the relative deviation of the current from other shifted normalized curves is recalculated, i.e., the new relative current deviation. And use a sliding window of length L to traverse each translation-normalized curve; if the currently traversed curve has k consecutive windows... Exceed If the current traversed curve is the disturbed curve, then the disturbed region is marked.

6. The method for diagnosing the aging state of oil-paper insulation based on depolarization current curves according to claim 5, characterized in that... S5 specifically refers to: Based on the dual-time translation factor, and using the reference curve as a reference, the reference current value corresponding to the interference region in each interference curve is calculated and replaced. Then, it is spliced ​​with the uninterrupted region to obtain the denoised curve.

7. A diagnostic device for the aging state of oil-paper insulation based on depolarization current curves, characterized in that, include: The reference curve unit is used to obtain the depolarization current curves at different discharge times, and select the depolarization current curve corresponding to a certain discharge time as the reference curve. The dual-time shift factor unit is used to select a certain current value of the reference curve as the base point and calculate the dual-time shift factor of the depolarization current curve at other discharge times. The translation normalization unit is used to map the depolarization current curves at different discharge times to the reference curve based on the calculated dual-time translation factor, so as to obtain the translation normalization curve. An interference identification unit is used to identify the interfered curve and its undisturbed and interfered regions based on the translational normalization curve. The denoising unit is used to denoise the disturbed area of ​​each translation normalized curve based on the reference curve, and to combine the denoised result with the undisturbed area to form a denoised curve. The diagnostic unit is used to diagnose the aging state of the oil-paper insulation based on the noise reduction curve and obtain the diagnostic results.

8. The device for diagnosing the aging state of oil-paper insulation based on depolarization current curves according to claim 7, characterized in that... The dual-time translation factor unit is specifically: In the reference curve A stable current value is selected as the base point, and the corresponding depolarization time is... ; Based on depolarization current curve Find the depolarization time corresponding to the current value closest to the base point. The dual-time translation factor is calculated, and its expression is as follows: ； in, Depolarization current curve At the point of time The two-time translation factor; This is the depolarization time.

9. A diagnostic device for the aging state of oil-paper insulation based on depolarization current curves according to claim 7, characterized in that... The translation normalization unit specifically refers to: The first depolarization current curve The time axis is adjusted to align with the reference curve. Alignment, according to the dual time translation factor The current value corresponding to each time point of the depolarization current curve after translation and normalization is calculated to obtain the translation and normalization curve.

10. A diagnostic device for the aging state of oil-paper insulation based on depolarization current curves according to claim 7, characterized in that... The interference identification unit specifically comprises: Calculate the relative current deviations of all translation-normalized curves from the reference curve: ； in, For the j-th translational normalized curve The relative deviation of the current; Set deviation threshold Overlap ratio threshold With the sliding window length L; The statistics show the percentage of regions in which the relative current deviation is less than a set deviation threshold in other shifted normalized curves besides the aforementioned baseline curve. ; If the regional proportion Less than the overlap ratio threshold Therefore, most of the shifted normalized curves have low overlap with the reference curve, and the relative current deviation between each pair of shifted normalized curves is low. Less than If most of the translational normalized curves overlap, the reference curve is the disturbed curve; from the overlapping translational normalized curves, the curve with the smallest relative current deviation is selected as the final reference curve. If the regional proportion Reaching the overlap ratio threshold If most of the translational normalized curves have a high degree of overlap with the reference curve, then the reference curve is retained as the final reference curve. Based on the final baseline curve, the relative deviation of the current from other shifted normalized curves is recalculated, i.e., the new relative current deviation. And use a sliding window of length L to traverse each translation-normalized curve; if the currently traversed curve has k consecutive windows... Exceed If the current traversed curve is the disturbed curve, then the disturbed region is marked.

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