Porcelain insulator operation life estimation method

Abstract

The invention discloses a method for estimating the service life of a porcelain insulator, which comprises the following steps of: calculating a weighted geometric mean value according to an actual bearing tension and a quick breaking tension value by adopting a small number of test samples, shortening the damage time of a test to a range of several hours to several months, and extrapolating the damage time under the actual tension according to the damage time. According to the method, the test time is long, and the longest test time of one group is close to one year, so that the service life estimation accuracy is high.

Description

Technical Field

[0001] The invention belongs to material science and engineering application technology, and in particular relates to a method for estimating the service life of a porcelain insulator. Background Art

[0002] Porcelain insulators are the most commonly used insulators at present. Insulators play the role of mechanical support and power insulation for transmission lines. After a fault occurs inside a porcelain insulator, the appearance often does not change, and the detection work is time-consuming and laborious. However, insulator failure will endanger the safe and stable operation of the power grid and affect social production. If the life of the insulator can be estimated, the inspectors can reasonably formulate the inspection plan and determine the inspection cycle. Estimating the operating life of porcelain insulators not only ensures the safety of the power grid, but also reduces the workload of inspection.

[0003] Porcelain insulators have stable chemical properties, long aging time, and are mostly damaged by long-term stress. It is a reasonable choice to estimate the life according to the actual tensile force. However, the actual damage time under tensile force is as long as ten years or even decades. The present invention calculates the weighted geometric mean based on the actual tensile force and the tensile force value of rapid breaking, shortens the test damage time to a range of several hours to several months, and extrapolates the damage time under actual tensile force based on this damage time. Summary of the invention

[0004] The purpose of the present invention is to provide a method for estimating the service life of a porcelain insulator, determine the test tension value according to the tension value that the porcelain insulator actually withstands and the tension value that quickly breaks; extrapolate the failure time under the actual tension according to the failure time under the test tension, and the life estimation accuracy is high.

[0005] The technical solution of the present invention is:

[0006] A method for estimating the service life of a porcelain insulator comprises the following steps:

[0007] (1) For a certain type of porcelain insulator, the actual tensile force it bears during long-term operation is determined and recorded as S 0 ;

[0008] (2) Take several porcelain insulators and perform breaking tests. Calculate the average breaking force, which is recorded as S. 1 ;

[0009] (3) Based on the tensile force S that the porcelain insulator bears during long-term operation 0 The average breaking force S of multiple porcelain insulators 1 , calculate the test tension F k ;

[0010] (4) In each test tension F kUnder the condition of M groups of tests, each group of tests is to connect N porcelain insulators in series to form an insulator string, and the two ends of the insulator string are subjected to F k The tensile force is recorded, and the failure time of each group of insulator strings being broken by the tensile force is recorded, and the order is arranged from small to large. k The tensile force, the mth failure time after sorting is T(k,m), where ;

[0011] (5) Calculate the derivative value p m , f k , t(k,m):

[0012] ;;

[0013] ;

[0014] ;

[0015] Where ln(*) is a function that calculates the natural logarithm;

[0016] (6) Using the above derivative values ​​t(k,m), p m , f k Perform multivariate linear fitting, fitting , get the values ​​of coefficients A, B, and C;

[0017] (7) Calculate the long-term tensile force S based on coefficients A, B, and C. 0 Operating life T 0 .

[0018] Preferably, the calculation of the long-term tensile force S in step (7) is 0 Operating life T 0 The method is:

[0019] ;

[0020] Where exp[*] is an exponential function with natural logarithm as base, A, B, C are the coefficients obtained from multivariate linear fitting in step (6), P 0 is the probability of damage to a single insulator, N is the number of insulators in each string of insulators tested in step (4), and N 0 It is the number of insulators contained in a certain insulator string in actual use.

[0021] Preferably, the method of the tensile test in step (2) is as follows: when producing and assembling the porcelain insulator, metal connectors with higher mechanical strength are used to ensure that the metal connectors are not damaged. The tensile value measured at this time reflects the performance of the porcelain part.

[0022] Preferably, the test tension F is calculated in step (3):k The method is:

[0023] ;

[0024] The value of k is 0.7 to 0.9.

[0025] Preferably, the values ​​of M and N in step (4) are N = 5 and M = 10.

[0026] Preferably, step (7) requires P 0 ≤5 / 10 5 .

[0027] The advantages of the present invention are:

[0028] The method for estimating the service life of porcelain insulators proposed by the present invention uses fewer test samples, calculates the weighted geometric mean according to the actual tensile force and the tensile force value of rapid breaking, shortens the test failure time to a range of several hours to several months, and extrapolates the failure time under actual tensile force based on this failure time. The test time of the method of the present invention is relatively long, and the longest test time of a group of tests is close to one year, so the life estimation accuracy is high. DETAILED DESCRIPTION

[0029] The method for estimating the service life of a porcelain insulator of the present invention takes a certain type of disc-type suspension porcelain insulator as an example and specifically comprises the following steps.

[0030] (1) The investigation confirmed that the actual tensile force that this type of porcelain insulator bears during long-term operation is S 0 =200 kN.

[0031] (2) Take 20 pieces of this type of porcelain insulators and use a tensile testing machine to measure the porcelain breaking strength in a short period of time. The 20 porcelain insulators are produced and assembled with metal connectors with higher mechanical strength to ensure that the metal connectors are not damaged. The measured breaking value at this time reflects the performance of the porcelain. The test results are: {1063, 1075, 976, 999, 1028, 1055, 1106,1036, 1113, 1074, 1109, 1056, 1017, 976, 1058, 1091, 1035, 1023, 1035, 995}. Calculate the average value as S 1 =1050 kN.

[0032] (3) Calculate the test tension F according to the following formula: k :

[0033] ;

[0034] Take parameters The test tensile force is .

[0035] (4) Carry out M = 10 sets of tests using the above tensile force. Each insulator string is composed of N = 5 porcelain insulators connected in series. For each set of tests, the time to break the insulator string must be recorded and sorted from small to large. Record the breaking time T (k, m) in hours, where The data is recorded in the following table:

[0036]

[0037] Among them, F k =694 kN, three groups of tests were not damaged for more than 8000 hours, so the damage time was not recorded. The lack of a small amount of data does not affect the use of the method of the present invention. k =753 ​​kN is missing a data point when testing.

[0038] (5) Calculate the derivative value p m , f k , t(k,m);

[0039] ;

[0040] ;

[0041] ;

[0042] Where ln(*) is the function for calculating the natural logarithm. The calculation results are shown in the following table:

[0043]

[0044] (6) Using the above derivative values ​​t(k,m), p m , f k Perform multivariate linear fitting, fitting Common numerical analysis software such as Excel and MATLAB have ready-made multivariate linear fitting functions that can be used. The coefficients A=176.7672, B=2.520903, and C=-25.664762 are obtained.

[0045] (7) Calculation of long-term tensile force S 0 Operating life T 0 :

[0046] ;

[0047] Where exp[*] is an exponential function with natural logarithm as base, A, B, C are the coefficients obtained from multivariate linear fitting in step (6), P 0 is the probability of damage to a single-piece insulator, usually requiring P0 ≤5 / 10 5 , N is the number of insulators in each string of insulators tested in step (4), N 0 It is the number of insulators contained in a certain insulator string in actual use.

[0048] The probability of single-piece insulator damage is P 0 =5 / 10 5 Consider a string of N 0 = 25 insulators in series, calculate the service life T 0 =77245 hours, or 8.8 years.

[0049] The method for estimating the service life of a porcelain insulator of the present invention calculates a weighted geometric mean value based on the actual tensile force and the tensile force value of rapid breaking, shortens the test failure time to a range of several hours to several months, and extrapolates the failure time under the actual tensile force based on the failure time. The test time of the method of the present invention is relatively long, and the longest test time of a group of tests is close to one year, so the life estimation accuracy is high.

[0050] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any modifications made according to the spirit of the main technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for estimating the service life of a porcelain insulator, characterized in that: Includes steps: (1) For a certain type of porcelain insulator, the actual tensile force it bears during long-term operation is confirmed by investigation, which is recorded as S0; (2) Take multiple porcelain insulators for breaking test and calculate the average breaking force, which is recorded as S1; (3) Calculate the test tensile force F based on the tensile force S0 that the porcelain insulator bears during long-term operation and the average breaking force S1 of multiple porcelain insulators. k ; (4) In each test tension F k Under the condition of M groups of tests, each group of tests is to connect N porcelain insulators in series to form an insulator string, and the two ends of the insulator string are subjected to F k The tensile force is recorded, and the failure time of each group of insulator strings being broken by the tensile force is recorded, and the order is arranged from small to large. k The tensile force, the mth failure time after sorting is T(k,m), where ; (5) Calculate the derivative value p m , f k , t(k,m): ； ； ； Where ln(*) is a function that calculates the natural logarithm; (6) Using the above derivative values ​​t(k,m), p m , f k Perform multivariate linear fitting, fitting , get the values ​​of coefficients A, B, and C; (7) Based on the coefficients A, B, and C, calculate the service life T0 when subjected to long-term tensile force S0.

2. The method for estimating the service life of a porcelain insulator according to claim 1, characterized in that: The method for calculating the service life T0 when subjected to long-term tensile force S0 in step (7) is: ； Where exp[*] is an exponential function with natural logarithm as base, A, B, C are the coefficients obtained by multivariate linear fitting in step (6), P0 is the probability of damage to a single insulator, N is the number of insulators contained in each insulator string tested in step (4), and N0 is the number of insulators contained in a certain insulator string when actually used.

3. The method for estimating the service life of a porcelain insulator according to claim 1, characterized in that: The method of the tensile test in step (2) is as follows: when producing and assembling porcelain insulators, metal connectors with higher mechanical strength are used to ensure that the metal connectors are not damaged. The tensile value measured at this time reflects the performance of the porcelain parts.

4. The method for estimating the service life of a porcelain insulator according to claim 1, characterized in that: Calculate the test tension F in step (3) k The method is: ； The value of k is 0.7 to 0.

9.

5. The method for estimating the service life of a porcelain insulator according to claim 1, characterized in that: The values ​​of M and N in step (4) are N = 5 and M = 10.

6. The method for estimating the service life of a porcelain insulator according to claim 2, characterized in that: Step (7) requires P0≤5 / 10 5 .

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