A method for estimating cumulative damage of typical defects of oil-paper insulation

Abstract

The application discloses an oil-paper insulation typical defect cumulative damage estimation method, 1, a partial discharge collection system is built, through oil-paper insulation typical defect discharge experiments, cumulative critical damage of a target device or a target model under the same electric stress form is calculated, and an oil-paper insulation typical defect cumulative critical damage model is established; 2, partial discharge detection is carried out on the target device or the target model, relevant discharge data are acquired, insulation cumulative damage is calculated, and through the established oil-paper insulation typical defect cumulative critical damage model, insulation damage rate of the target device or the target model is obtained. The method can calculate insulation cumulative damage of the oil-filled device in a current period, and determine the insulation damage rate, and can effectively estimate the cumulative damage condition of the oil-paper insulation typical defect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil-filled equipment damage estimation, and particularly relates to a method for estimating cumulative damage of typical defects of oil-paper insulation. BACKGROUND

[0002] Oil-paper insulation system is a widely used insulation structure in electrical equipment, and its working state is crucial for the long-term safe operation of the equipment. As the operation life of power equipment increases, the aging and damage of oil-paper insulation materials gradually appear, and various defects that may exist in the insulation system can significantly increase the possibility of partial discharge, thereby accelerating the degradation of insulation performance. Therefore, accurately assessing the damage condition of oil-paper insulation is of great significance for preventing electrical equipment failure and ensuring the stable operation of power systems.

[0003] Existing oil-paper insulation damage assessment methods can reflect the damage condition of insulation materials to some extent, but still have some deficiencies, which limit their reliability in practical application.

[0004] Firstly, the existing damage assessment methods do not fully consider the defect conditions in the insulation system. Typical defects inside the oil-paper insulation material, such as air gap, impurities, mechanical damage, etc., can cause severe distortion of the electric field, significantly increasing the local electric field strength, which is a key factor for inducing partial discharge and insulation damage. Traditional assessment methods often ignore the existence of these microscopic defects, and cannot accurately quantify the performance degradation of the equipment due to defects, resulting in deviation between the damage assessment results and the actual situation.

[0005] Secondly, the existing damage assessment methods lack quantitative evaluation based on discharge mechanism. Partial discharge is an early signal of the decline of insulation performance in oil-paper insulation materials, while most existing assessment methods are based on the measurement of macroscopic physical quantities, such as insulation resistance, dielectric loss, etc., ignoring the key role of discharge behavior in the insulation damage process. Due to the complexity of discharge mechanism, the current assessment methods fail to effectively combine the discharge mechanism to quantitatively analyze the degree of insulation damage, resulting in the evaluation results failing to accurately reflect the actual damage condition of the insulation material.

[0006] In addition, most existing assessment methods do not consider the cumulative effect of discrete partial discharge behavior. The damage of oil-paper insulation is often the result of long-term accumulation of partial discharge behavior, and the superposition of discrete partial discharge events in time dimension can accelerate the degradation of insulation materials. However, the current damage assessment methods generally lack consideration of this cumulative effect, and the assessment model cannot reflect the long-term effect of partial discharge, resulting in deviation of the damage assessment results from the actual insulation damage condition. SUMMARY

[0007] To solve the problems in the prior art, the oil-paper insulation typical defect cumulative damage estimation method aims to comprehensively consider the influence of insulation defects, quantitatively evaluate the insulation damage condition based on a discharge mechanism, and fully consider the cumulative effect of discrete partial discharge behaviors, so as to improve the accuracy and reliability of damage evaluation and ensure the safe and stable operation of oil-filled electrical equipment.

[0008] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0009] An oil-paper insulation typical defect cumulative damage estimation method comprises the following steps:

[0010] S100: A partial discharge collection system is built, and the cumulative critical damage of a target device or a target model under the same electric stress form is calculated through oil-paper insulation typical defect discharge experiments, and an oil-paper insulation typical defect cumulative critical damage model is established;

[0011] S200: The partial discharge of the target device or the target model is detected, relevant discharge data is obtained, the insulation cumulative damage amount is calculated, and the insulation damage rate of the target device or the target model is obtained through the established oil-paper insulation typical defect cumulative critical damage model.

[0012] Further, the target device includes but is not limited to an oil-paper insulation online running device such as a transformer and a reactor, the target device includes but is not limited to an oil-paper insulation device such as a transformer and a reactor, and the target model includes but is not limited to a laboratory discharge model such as a scaled-down model and an abstract model; the detection method adopted by the partial discharge collection system includes but is not limited to a pulse current method, an ultrahigh frequency detection method, an ultrasonic detection method, and a light detection method.

[0013] Further, the method is suitable for various detection scenes and is not only suitable for laboratory models but also suitable for online running devices.

[0014] Further, the method is suitable for various electric stress forms, including insulation damage condition evaluation under different voltage frequencies and voltage waveforms.

[0015] Further, in step S100, the process of establishing the oil-paper insulation typical defect cumulative critical damage model is as follows:

[0016] S101: For the target device or the target model, a partial discharge collection system is disposed;

[0017] S102: A plurality of same-type defect discharge experiments are performed under the same electric stress form, and the partial discharge collection system continuously collects and stores all discharge data;

[0018] S103: An appropriate statistical time T is selected h , and the statistical time T ish Divide the time period, calculate the total discharge amplitude of each time period of insulation damage stage The time period with the largest total discharge amplitude appears The time period with the largest total discharge amplitude appears The expression of the cumulative critical damage of the target device or target model in a single experiment is constructed The expression of the cumulative critical damage of the target device or target model in a single experiment is constructed The expression of the cumulative critical damage D of the target device or target model under a given electric stress form is constructed C,Th The expression of the cumulative critical damage D of the target device or target model under a given electric stress form is constructed

[0019] S104: Set the initial value n of the damage coefficient required for calculating the cumulative critical damage expression, the change step δ, and the calculation precision δ j = 0, the change step δ, and the calculation precision δ C , and the calculation times are j;

[0020] S105: Calculate the cumulative critical damage D C,Th (k) of each experiment according to the cumulative critical damage expression of the target device or target model in a single experiment, and calculate the coefficient of variation C V of the cumulative critical damage of each repeated experiment under the same electric stress form, and the jth calculation result is and

[0021] S106: Set the calculation result of the j-1th coefficient of variation when j = 1 Compare the calculation result of the jth coefficient of variation with the calculation result of the j+1th coefficient of variation and the calculation result of the j-1th coefficient of variation ; if and go to step S107, otherwise let j = j + 1 and n j = n j-1 + δ, and return to step S105;

[0022] S107: Compare the calculation result of the jth coefficient of variation with the set calculation precision δ C ; if go to step S108, otherwise let j = 1 and δ = δ / 2, and return to step S105;

[0023] S108: Take the value of n j calculated last time as the damage coefficient of the target device or target model, and calculate the cumulative critical damage D of the target device or target model under a given electric stress form, and get the cumulative critical damage model of typical defects of oil-paper insulation.

[0024] Furthermore, in step S102, the defect discharge experiment ends with the breakdown of a typical defect in the oil-paper insulation, and the stress applied includes constant stress, step stress, and sequential stress.

[0025] In step S103, the appropriate statistical duration T is set. h The value of the balance T h The dispersion of small single discharge events leads to instability in the determination and assessment of damage initiation, and T h The impact of excessively large values ​​on the evaluation results should be determined based on the model parameters of the target equipment or model and the actual operating conditions.

[0026] Furthermore, in step S103, the basis The cumulative critical damage of a single experimental target device or target model The expression is:

[0027]

[0028] In the formula, k is the experiment number; For the i-th statistical duration T h The total discharge amplitude of the divided time intervals; N b To achieve the highest total discharge amplitude in history The time period is the starting point of the timing, and the value of i corresponds to the termination time of the electrical aging of the defect discharge experiment; n is the damage coefficient; w k Let be the discharge characteristic quantity of the k-th experiment.

[0029] Furthermore, the discharge characteristic quantity w of the k-th experiment k Dimensionless quantities that can characterize the differential features of the discharge data in this experiment include average discharge amplitude, maximum discharge amplitude, or discharge repetition rate.

[0030] Furthermore, in step S103, the basis Cumulative critical damage of the target device or target model under a given form of electrical stress The expression is:

[0031]

[0032] In the formula, N k The effective number of discharge experiments for the same type of defect under the same electrical stress condition.

[0033] Furthermore, in step S104, the change step size δ is the damage coefficient n. j The step size in the iterative calculation needs to be set according to the calculation speed and the accuracy requirements of the actual damage assessment. The reference range is 10. -4~10 -1 .

[0034] Further, in step S104, the calculation precision δ C is the coefficient of variation The maximum allowable value, the specific value needs to be set in combination with the effective number of defect discharge experiments and discharge characteristics, and the reference range is 0-0.5.

[0035] Further, in step S105, the coefficient of variation C V is expressed as:

[0036]

[0037] In the formula, is the standard deviation of the cumulative critical damage of k experiments; is the average value of the cumulative critical damage of k experiments.

[0038] Further, in step S200, the estimation process of the insulation damage rate of the target device or target model is as follows:

[0039] S201: Data acquisition is performed using a partial discharge acquisition system, a tracking step T p is set, and the discharge characteristic value F in the tracking interval is calculated;

[0040] S202: A data storage threshold value F t is set, when the discharge characteristic value F in the tracking interval during the acquisition process exceeds the data storage threshold value F t , the partial discharge acquisition system enters a continuous acquisition and data storage mode, and step S203 is entered, otherwise, step S201 is returned;

[0041] S203: The partial discharge acquisition system continuously acquires and stores all discharge data, and divides time intervals with a statistical time length T h , taking the discharge time of the stored maximum discharge total amplitude as the time start, and calculates the discharge total amplitude in the i-th time interval;

[0042] S204: The historical maximum discharge total amplitude is set when i=1, the discharge total amplitude in the i-th time interval is compared with the value of the historical maximum discharge total amplitude , if step S205 is entered, otherwise, the historical maximum discharge total amplitude is updated and step S203 is returned;

[0043] S205: total discharge amplitude of each time period in the insulation damage stage calculating the cumulative damage of the insulation from the damage initiation stage to the i-th time period

[0044] S206: cumulative critical damage of the target device or target model under a given electric stress form determined according to the cumulative critical damage model of typical defects of oil-paper insulation calculating the insulation damage rate of the i-th time period thereby characterizing the damage condition of the insulation.

[0045] Further, in step S201, the tracking interval is defined as a time interval before the current time with a width of a tracking step T p The specific value of the tracking step T p is determined according to the collection mode and collection parameters of the partial discharge collection system.

[0046] Further, in step S201, the discharge characteristic value F includes but is not limited to the total discharge frequency per unit time, the average discharge amplitude, and the acetylene generation amount, wherein the definition of the unit time includes but is not limited to per second, per minute, and per power frequency cycle.

[0047] Further, in step S202, the data storage threshold value F t corresponds to the discharge characteristic value F, and by setting an appropriate value of F t , the development of the insulation partial discharge is determined, thereby changing the working mode of the partial discharge collection system and effectively collecting the discharge data of the damage stage; the specific value of the data storage threshold value F t needs to be set in combination with the design parameters and actual operation of the target device or target model.

[0048] Further, a maximum amplitude overflow percentage a% is set for the historical maximum discharge total amplitude during the process of discriminating and updating, and the case where the historical maximum discharge total amplitude is not exceeded is not updated.

[0049] Further, in step S205, the cumulative damage of the insulation from the damage initiation stage to the i-th time period is defined as:

[0050]

[0051] In the formula, N i is the i value corresponding to the i-th time period with the time period when the historical maximum discharge total amplitude appears as the time starting point; and w is the discharge characteristic quantity of the insulation partial discharge.

[0052] Further, in step S206, the insulation damage rate of the i th time interval is calculated according to the cumulative critical damage of the target device or the target model under the given electric stress form and the cumulative damage of the insulation from the damage initiation stage to the i th time interval. is defined as:

[0053]

[0054] wherein, is the cumulative damage of the insulation from the damage initiation stage to the i th time interval; is the cumulative critical damage of the target device or the target model under the given electric stress form.

[0055] The present application has the following advantages: the method fully considers the damage of the insulation caused by the partial discharge under the typical defect of the oil-paper insulation, and the life estimation result is more suitable for the actual operation of the oil-filled equipment; the method is based on the physical mechanism of the partial discharge, considers the variation characteristics of the discharge amplitude in the insulation damage stage, quantitatively estimates the insulation damage caused by the partial discharge induced by the typical defect, establishes the cumulative critical damage expression of the oil-filled equipment under the given electric stress form, and calculates the insulation damage rate of the oil-filled equipment at the current time according to the cumulative critical damage, so as to represent the damage condition of the insulation and provide a reference for the cumulative damage condition estimation of the oil-filled equipment insulation; the method fully considers the cumulative effect of the insulation damage caused by the partial discharge, discretizes the cumulative discharge total amplitude of the discharge events in the continuous time at intervals of the unit statistical time length, and is more conducive to the equivalent simulation of the cumulative damage of the insulation by the discrete discharge events in the time scale; the method uses a wide range of data sources for constructing the cumulative critical damage, and the data sources can be obtained by various local measurement techniques which have been developed maturely in engineering applications, so the method has low acquisition difficulty and high operability. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 is the flow chart of the method.

[0057] Figure 2 is the relationship diagram of the statistical time length and the variation coefficient under the 50Hz, 150Hz and 250Hz sine waveforms. DETAILED DESCRIPTION

[0058] The present application will be further described in detail below in combination with the drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0059] As shown in the drawings, Figure 1 An oil-paper insulation typical defect cumulative damage estimation method includes the following steps:

[0060] S100: A partial discharge collection system is built, the cumulative critical damage of the target device or the target model under the same electric stress form is calculated through the discharge experiment of the oil-paper insulation typical defect, and an oil-paper insulation typical defect cumulative critical damage model is established.

[0061] S200: Perform partial discharge detection on the target equipment or target model, obtain relevant discharge data, calculate the cumulative insulation damage, and obtain the insulation damage rate of the target equipment or target model through the established cumulative critical damage model of typical defects in oil-paper insulation.

[0062] Furthermore, in step S100, the process of establishing the cumulative critical damage model for typical defects in oil-paper insulation is as follows:

[0063] S101: Install a partial discharge acquisition system for the target device or target model;

[0064] S102: Multiple discharge experiments of the same type of defect are conducted under the same electrical stress, and the partial discharge acquisition system continuously acquires and stores all discharge data.

[0065] S103: Select the appropriate statistical duration T h , based on the statistical duration T h Divide the process into time periods and calculate the total discharge amplitude for each time period during the insulation damage stage. The highest total discharge amplitude in history was observed. The time period is used as the starting point for timing, and a system based on... The cumulative critical damage of a single experimental target device or target model Expressions and based on Cumulative critical damage of the target device or target model under a given form of electrical stress The expression;

[0066] S104: Set the initial value n of the damage coefficient required for calculating the cumulative critical damage expression parameters. j =0, step size δ and calculation accuracy δ C The number of calculations is j;

[0067] S105: Calculate the cumulative critical damage for each experiment based on the cumulative critical damage expression of the target equipment or target model in a single experiment. And calculate the coefficient of variation C of the cumulative critical damage for each repeated experiment under the same electrical stress condition. V The result of the j-th calculation is and

[0068] S106: Calculation results of the coefficient of variation for the (j-1)th iteration when j=1. Compare the calculated results of the j-th coefficient of variation The calculation result of the coefficient of variation for the (j+1)th time The result of the calculation of the coefficient of variation of the (j-1)th time The magnitude of the value; if and Go to step S107, otherwise let j = j + 1 and n j = n j-1 + δ, and return to step S105;

[0069] S107: compare the calculation result of the jth variation coefficient with the numerical value of the set calculation precision δ C ; if go to step S108, otherwise let j = 1 and δ = δ / 2, and return to step S105;

[0070] S108: take the last calculated n j value as the damage coefficient of the target device or target model, and calculate the cumulative critical damage of the target device or target model under a given electrical stress form to obtain a cumulative critical damage model of typical defects of oil-paper insulation.

[0071] Further, in step S200, the estimation process of the insulation damage rate of the target device or target model is as follows:

[0072] S201: use the partial discharge acquisition system to collect data, set the tracking step size T p , and calculate the discharge characteristic value F in the tracking interval;

[0073] S202: set the data storage threshold value F t , when the discharge characteristic value F in the tracking interval during the acquisition process exceeds the data storage threshold value F t , the partial discharge acquisition system enters the continuous acquisition and data storage mode, and goes to step S203, otherwise, return to step S201;

[0074] S203: the partial discharge acquisition system continuously acquires and stores all discharge data, and divides the time period with the time start at the discharge time of the stored maximum discharge total amplitude and the statistical time length T h , and calculates the discharge total amplitude in the ith time interval

[0075] S204: set the historical maximum discharge total amplitude when i = 1, compare the discharge total amplitude in the ith time interval with the numerical value of the historical maximum discharge total amplitude ; if go to step S205, otherwise update the historical maximum discharge total amplitude and return to step S203;

[0076] S205: according to the discharge total amplitude of each time period in the insulation damage stage Calculate the cumulative insulation damage from the initial damage stage to the i-th time period.

[0077] S206: The cumulative critical damage of the target equipment or target model under a given electrical stress form, determined based on the cumulative critical damage model of typical defects in oil-paper insulation. Calculate the insulation damage rate in the i-th time period This characterizes the damage status of the insulation.

[0078] Example

[0079] The feasibility of the method of this invention is illustrated by taking the inter-panel electrical stress waveform of the YYD valve-side winding of the converter transformer and the sinusoidal voltage waveforms of different frequencies output from the simulation circuit model of an ±800kV DC transmission system. Based on the method of this invention, multiple sets of partial discharge experiments on the tip defects of the oil-paper insulation were conducted under different electrical stress waveforms to determine the occurrence of the historical maximum total discharge amplitude. The time period is used as the starting point for characterizing the onset of damage, and the time period at which the electrical aging of the defect discharge experiment ends is used as the damage endpoint, with the statistical duration T as the starting point. h Divide the time period and calculate the total discharge amplitude of each time period during the damage stage. The values ​​are calculated using formula (2) to determine the sinusoidal voltage waveforms of different frequencies and to simulate the cumulative critical damage under the inter-plate electrical stress of the YYD converter valve side winding.

[0080] Figure 2 The display shows different statistical durations T under 50Hz, 150Hz, and 250Hz sine waveforms. h For the coefficient of variation C V The impact is shown in Table 1, which presents the statistical duration T. h With coefficient of variation C V The specific value. From Figure 2 As shown in Table 1, the statistical duration T h Within the range of 2s to 30s, the coefficients of variation of cumulative critical damage at various frequencies obtained from cyclic calculations show certain commonalities, with overall values ​​exhibiting significant fluctuations over the statistical duration T. h When the coefficient of variation C is small V The value is relatively large, and then increases with the statistical duration T. h As it continues to increase, the coefficient of variation C V It shows a fluctuating increasing trend, considering T h When the value is slightly larger, for high-frequency groups with shorter damage accumulation times, the number of damage time periods divided by statistical duration is small, resulting in fewer effective data points. Therefore, considering the above factors, T is selected. h =2s is used as the statistical duration.

[0081] Table 1: Statistical duration and coefficient of variation for 50Hz, 150Hz, and 250Hz sine waves

[0082]

[0083] Considering that the main harmonic content of the simulated inter-panel electrical stress waveform of the YYD valve-side winding of the converter transformer is odd harmonics, this embodiment presents the damage coefficient n and cumulative critical damage for the model under the power frequency, the main odd harmonic frequency, and the simulated inter-panel electrical stress waveform of the YYD valve-side winding of the converter transformer. The calculation results are shown in Table 2. The damage coefficient n tends to decrease with increasing frequency, while the damage coefficient n under the simulated inter-plate electrical stress waveform of the YYD valve-side winding of the converter transformer is between the damage coefficients of the power frequency and various harmonics. The cumulative critical damage of a specific voltage waveform is utilized. Based on the cumulative damage in the current period The insulation damage rate can be calculated. This characterizes the damage status of the insulation.

[0084] Table 2: Model parameters for various voltage frequencies and waveforms

[0085]

[0086] In this embodiment, the statistical duration T h Take 2 seconds, the historical maximum total discharge amplitude The initial value is set to 0kV. The acquisition period and tracer step size T of the partial discharge acquisition system are set accordingly. p All tests were conducted for 1 minute, and the effective number of tests N for the same type of defect discharge under the same electrical stress was recorded. k The value is set to 5, the step size δ is set to 0.01, and the calculation accuracy δ is set to 0.01. C Take 0.40. Discharge characteristic quantity w k Defined as the dimensionless average discharge amplitude, the discharge characteristic value F is defined as the discharge repetition rate in seconds, and the data storage threshold value F t The value is set to 100. For any time period within the damage stage, the method of this invention can calculate the cumulative damage amount of the insulation up to that time period. The cumulative critical damage value was determined by combining the cumulative critical damage model of typical defects in oil-paper insulation. Calculate the insulation damage rate during this period.

Claims

1. A method for estimating the cumulative damage of typical defects in oil-paper insulation, characterized in that, Includes the following steps: S100: Build a partial discharge acquisition system, calculate the cumulative critical damage of the target equipment or target model under the same electrical stress form through discharge experiments of typical defects in oil-paper insulation, and establish a cumulative critical damage model of typical defects in oil-paper insulation. S200: Perform partial discharge detection on the target equipment or target model, obtain relevant discharge data, calculate the cumulative insulation damage, and obtain the insulation damage rate of the target equipment or target model through the established cumulative critical damage model of typical defects in oil-paper insulation. In step S100, the process of establishing the cumulative critical damage model of typical defects in oil-paper insulation is as follows: S101: Install a partial discharge acquisition system for the target device or target model; S102: Multiple discharge experiments of the same type of defect are conducted under the same electrical stress, and the partial discharge acquisition system continuously acquires and stores all discharge data. S103: Select the appropriate statistical duration Based on the duration Divide the process into time periods and calculate the total discharge amplitude for each time period during the insulation damage stage. The highest total discharge amplitude in history was observed. The time period is used as the starting point for timing, and a system based on... The cumulative critical damage of a single experimental target device or target model Expressions and based on Cumulative critical damage of the target device or target model under a given form of electrical stress The expression; The basis The single experiment and the cumulative critical damage of the target device or target model under a given electrical stress form. The expression is: （1） In the formula, Experiment number; For the first Statistical duration The total discharge amplitude within the divided time intervals; To achieve the highest total discharge amplitude in history The time period is the starting point of the timing, and the timing number is the time corresponding to the end time of the electrical aging of the defect discharge experiment. Damage coefficient; For the first Discharge characteristic quantities of this experiment; The basis Cumulative critical damage of the target device or target model under a given form of electrical stress The expression is: （2） In the formula, The effective number of discharge experiments for the same type of defect under the same electrical stress condition; S104: Set the initial values ​​of the damage coefficients required for calculating the cumulative critical damage expression parameters. , change step size and calculation accuracy The number of calculations is ; S105: Calculate the cumulative critical damage for each experiment based on the cumulative critical damage expression of the target equipment or target model in a single experiment. And calculate the coefficient of variation of cumulative critical damage for each repeated experiment under the same electrical stress form. , No. The result of the calculation is and ; S106: Settings Time Calculation results of the coefficient of variation Comparison of the first Calculation results of the coefficient of variation , No. Calculation results of the coefficient of variation With the Calculation results of the coefficient of variation The magnitude of the value; if and Proceed to step S107, otherwise... and And return to step S105; S107: Comparison of Section Calculation results of the coefficient of variation With the set calculation precision The magnitude of the value; if Proceed to step S108, otherwise... and And return to step S105; S108: Take the last calculated value. The value is the damage coefficient of the target device or target model, and the cumulative critical damage of the target device or target model under a given electrical stress form is calculated. A cumulative critical damage model for typical defects in oil-paper insulation was obtained; In step S200, the estimation process for obtaining the insulation damage rate of the target device or target model is as follows: S201: Use a partial discharge acquisition system to acquire data and set the tracer step size. Calculate the discharge characteristic value within the tracer interval. ; S202: Set data storage threshold value During the acquisition process, the discharge characteristic value within the tracer interval Exceeding the data storage threshold When the partial discharge acquisition system switches to continuous acquisition and data storage mode, proceed to step S203; otherwise, return to step S201. S203: The partial discharge acquisition system continuously acquires and stores all discharge data, including the historical maximum total discharge amplitude. The discharge time is taken as the starting point for the statistical duration. Divide the time period and calculate the first Total discharge amplitude within each time interval ; S204: Settings Maximum total discharge amplitude in history Comparison of the first Total discharge amplitude within each time interval Compared with the historical maximum total discharge amplitude The magnitude of the value, if Proceed to step S205; otherwise, update the historical maximum total discharge amplitude. and return to step S203; S205: Based on the total discharge amplitude at each time point during the insulation damage stage. Calculate from the initial stage of damage to the... Cumulative insulation damage over a time period The process from the initial stage of damage to the... Cumulative insulation damage over a time period Defined as: （4） In the formula, To achieve the highest total discharge amplitude in history The time period is the starting point of the timekeeping, the first The time number corresponding to each time period; This refers to the discharge characteristic quantity of partial discharge in insulation; S206: The cumulative critical damage of the target equipment or target model under a given electrical stress form, determined based on the cumulative critical damage model of typical defects in oil-paper insulation. Calculate the first Insulation damage rate over a period of time This characterizes the damage status of the insulation; The first Insulation damage rate over a period of time Defined as: （5） In the formula, From the initial stage of injury to the... The cumulative amount of insulation damage over a period of time; This refers to the cumulative critical damage of the target device or target model under a given electrical stress form.

2. The method for estimating the cumulative damage of typical defects in oil-paper insulation as described in claim 1, characterized in that, The target equipment includes online operating equipment with oil-paper insulation such as transformers and reactors; the target models include scaled-down models and abstract models of laboratory discharge models; the detection methods used in the partial discharge acquisition system include pulse current method, ultra-high frequency detection method, ultrasonic detection method, or optical detection method.

3. The method for estimating the cumulative damage of typical defects in oil-paper insulation as described in claim 1, characterized in that, This method is applicable to various forms of electrical stress, including the assessment of insulation damage under different voltage frequencies and voltage waveforms.

4. The method for estimating the cumulative damage of typical defects in oil-paper insulation as described in claim 1, characterized in that, In step S102, the defect discharge experiment ends with the breakdown of a typical defect in the oil-paper insulation, and the stress is applied in the form of constant stress, step stress, and sequential stress.

5. The method for estimating the cumulative damage of typical defects in oil-paper insulation as described in claim 1, characterized in that, In step S104, the change step size Damage coefficient The step size in the iterative calculation needs to be set according to the calculation speed and the accuracy requirements of the actual damage assessment. The reference range is 10. -4 ~ 10 -1 .

6. The method for estimating the cumulative damage of typical defects in oil-paper insulation as described in claim 1, characterized in that, In step S104, the calculation accuracy Coefficient of variation The maximum allowable value needs to be set based on the effective number of defect discharge experiments and the discharge characteristics. The reference range is 0 to 0.

5.

7. The method for estimating the cumulative damage of typical defects in oil-paper insulation as described in claim 1, characterized in that, In step S105, the coefficient of variation The expression is: （3） In the formula, for Accumulated critical damage in this experiment Standard deviation; for Accumulated critical damage in this experiment The average value.

8. The method for estimating the cumulative damage of typical defects in oil-paper insulation as described in claim 1, characterized in that, The first Discharge characteristic quantities of this experiment Dimensionless quantities that can characterize the differential features of the discharge data in this experiment include average discharge amplitude, maximum discharge amplitude, or discharge repetition rate.

9. The method for estimating the cumulative damage of typical defects in oil-paper insulation as described in claim 1, characterized in that, In step S201, the tracer interval is defined as the interval with a width equal to the tracer step size before the current time. Time interval, tracer step size The specific value is determined based on the acquisition method and acquisition parameters of the partial discharge acquisition system.

10. The method for estimating the cumulative damage of typical defects in oil-paper insulation as described in claim 1, characterized in that, In step S201, the discharge characteristic value This includes the total number of discharges per unit time, the average discharge amplitude, or the amount of acetylene generated. The unit time is defined as per second, per minute, or per power frequency cycle.

11. The method for estimating the cumulative damage of typical defects in oil-paper insulation as described in claim 1, characterized in that, In step S202, the data storage threshold value With discharge characteristic value Correspondingly, by setting the adaptation The numerical value is used to determine the development of partial discharge in the insulation, thereby changing the working mode of the partial discharge acquisition system to effectively collect discharge data during the damage stage; data storage threshold value. The specific values ​​need to be set based on the design parameters of the target equipment or target model and the actual operating conditions.

12. The method for estimating the cumulative damage of typical defects in oil-paper insulation as described in claim 1, characterized in that, Allowed to the historical maximum total discharge amplitude During the judgment update process, a maximum overflow percentage is set for it. %, for no more than The current situation will not be updated.

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