A method for determining replacement standards for electrical equipment taking into account evaluation errors

Abstract

The present invention provides a method for determining replacement standards for electrical equipment taking into account evaluation errors. The method establishes a distribution curve between key parameters that determine the life of the equipment and the equipment operating time, obtains the relationship between the equipment failure probability and the key parameters, and considers the errors in the key parameter evaluation method to establish a model to calculate the full life cycle cost, thereby obtaining the equipment replacement standard when the economy is optimal. This solves the economic waste caused by replacing equipment based on the service life of the equipment, takes into account the impact of evaluation errors on the equipment replacement standard, improves the rationality and accuracy of the equipment replacement standard, significantly improves the service life of electrical equipment and the economic benefits of the power grid, and provides guidance for the replacement of electrical equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrical equipment replacement standards, and in particular relates to a method for determining electrical equipment replacement standards by taking evaluation errors into consideration. Background Art

[0002] The performance of electrical equipment gradually declines with the increase of service time. When the performance of equipment cannot meet the needs of the site, major accidents will occur and cause huge economic losses. Therefore, power companies need to replace electrical equipment regularly to avoid accidents. The existing replacement standards are based only on the operating life of electrical equipment, and do not consider the impact of the equipment operating environment on the deterioration of the equipment status. The degree of equipment deterioration in harsh environments is underestimated, resulting in safety risks; the equipment in a good operating environment is overestimated, resulting in a waste of the remaining life of the equipment. Even for a small number of companies that replace equipment according to the status of the equipment, the impact of the evaluation error on the equipment replacement has not been quantified, and only relatively conservative equipment replacement standards can be selected. Although the safety risk of equipment operation is reduced, it still causes a waste of the economic value of the equipment. Therefore, the replacement standard of electrical equipment considering the evaluation error and the determination of the equipment inspection cycle are important issues that need to be solved in the field of electrical equipment operation and maintenance. Summary of the invention

[0003] In view of the above problems, the purpose of the present invention is to provide a method for determining the replacement standard of electrical equipment taking into account evaluation errors. By establishing a distribution curve of key parameters of equipment life and equipment operating time, the relationship between equipment failure probability and key parameters is obtained, and the errors of the key parameter evaluation method are taken into account, a model is established to calculate the full life cycle cost, and the equipment replacement standard when the economy is optimal is obtained. This solves the economic waste caused by replacing equipment based on the service life of the equipment, takes into account the impact of evaluation errors on equipment replacement standards, improves the rationality and accuracy of equipment replacement standards, and significantly improves the service life of electrical equipment and the economic benefits of the power grid.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for determining a replacement standard for electrical equipment taking into account an evaluation error comprises the following steps:

[0006] 1) Based on the historical data of electrical equipment operation and maintenance and experimental statistical results, establish the failure probability distribution curve g(l) of the equipment as the equipment status parameter l changes and the distribution probability curve Q of the equipment status parameter l in the kth year of use k (l), and calculate the equipment failure probability distribution curve fl(k) in the kth year;

[0007] The step 1) comprises the following steps:

[0008] 1.1) Based on the equipment failure history data, calculate the failure probability distribution curve g(l) of the equipment state quantity l;

[0009] 1.2) According to the historical data of equipment operation and maintenance, the distribution probability curve Q of the equipment status parameter l in the kth year is fitted and calculated k (l);

[0010] 1.3) Calculate the equipment failure probability distribution curve fl(k) in the kth year;

[0011]

[0012] Where: fl(k) is the equipment failure probability distribution curve in the kth year of use, Q k (l) is the distribution probability curve of the equipment state parameter l in the kth year of use, g(l) is the failure probability distribution curve of the equipment as the state parameter l changes, l max and l min are the maximum and minimum values ​​of the device state parameter l respectively;

[0013] 2) Through experiments, the true value of the equipment state parameter l is obtained real and the evaluation value l estimation The average error between The actual value of the device status parameter l real is the expected value, the average error is the standard deviation, and the evaluation parameter l is obtained estimation Distribution probability curve h(l estimation );

[0014] 3) When the parameter evaluation value is less than l c When the device is replaced, the actual value of the device state parameter is calculated to be l r When the device is replaced, the probability r(l r );

[0015]

[0016] Where: r(l r ) is the true value of the device state parameter l r The probability of being replaced when r ) is the true value of the device state parameter l r Distribution curve of evaluation value, l c The equipment is replaced when the equipment status parameter evaluation value is less than l c When replaced, l min is the minimum value of the state parameter l;

[0017] 4) Calculate the probability of replacing the equipment in the kth year of operation as the probability that the equipment status parameter evaluation value is less than the equipment replacement standard lc probability;

[0018]

[0019] Where: re(k) is the probability of replacing a device that has been in operation for k years;

[0020] 5) Establish a calculation model, input the calculation model parameters, the total number of devices N, the calculation cycle n, and obtain the replaced device matrix Failed Device Matrix and testing equipment matrix The step 5) comprises the following steps:

[0021] 5.1) Establish a device collection matrix Replaced Device Matrix Failed Device Matrix and testing equipment matrix The above matrices are all n-order matrices;

[0022] 5.2) Calculate the number of equipment replaced in year j that has been used for k years NR j,k and the number of failures NF j,k , update the replaced device matrix and failed device matrix Calculate the number of devices that have been used for k+1 years in year j+1. j+1,k+1 ;

[0023] The number of devices replaced each year is calculated as:

[0024] NR j,k =NA j,k *re(k) (Formula 4)

[0025] Among them: NR j,k is the number of equipment replaced in year j after being used for k years, NA j,k is the number of devices with a usage period of k years in year j;

[0026] The number of failed devices each year is calculated as:

[0027] NF j,k =NA j,k *fl(k) (Formula 5)

[0028] Where: NF j,k is the number of equipment failures in the jth year after k years of use;

[0029] The number of new equipment invested in year j+1 is calculated as:

[0030]

[0031] Among them: NAj+1,1 is the number of new equipment invested in year j+1, NR j,k is the number of equipment that has been used for k years and replaced in year j;

[0032] Calculate the number of devices that have been used for k+1 years in year j+1. j+1,k+1

[0033] NA j+1,k+1 =NA j,k -NF j,k -NR j,k (Formula 7)

[0034] Among them: NA j+1,k+1 is the number of devices used in year k+1 in year j+1;

[0035] 6) Input the equipment unit failure cost FC, unit replacement cost RC, unit inspection cost DC and annualized interest rate η to calculate the life cycle cost LCC;

[0036] 6.1) Calculate the total cost C required to handle equipment failure TFC for:

[0037]

[0038] Where: C TFC is the total cost of handling equipment failures, FC is the cost of maintaining a single failed device, and NF j,k is the number of equipment failures in the jth year after k years of use, and η is the annualized interest rate;

[0039] 6.2) Calculate the total cost C required to replace the equipment TRC for:

[0040]

[0041] Where: C TRC is the total cost of replacing the equipment, NR j,k is the number of equipment that has been used for k years and is replaced in year j, and RC is the cost required to replace a single equipment;

[0042] 6.3) Starting from t, the equipment is tested every year. The number of tested equipment each year is calculated as:

[0043]

[0044] Calculate the total testing cost C TDC for:

[0045]

[0046] Where: C TDCis the total equipment inspection cost within the calculation period, DC is the cost required to inspect a single device, and ND j,k is the number of equipment inspections in the jth year with k years of operation;

[0047] 6.4) Based on the results obtained in step 6.1), step 6.2) and step 6.3), output the life cycle cost:

[0048] LCC lc,t =C TIC +C TRC +C TFC +C TDC (Formula 12)

[0049] Where: C TIC is the initial investment cost of the equipment during the calculation period, LCC lc,t The standard for equipment replacement is l c , the full life cycle cost of the equipment when the first inspection time is t;

[0050] 7) Calculate the life cycle cost under different equipment replacement standards and initial inspection years to obtain the life cycle cost matrix Get the replacement standard with the lowest life cycle cost ci and equipment initial inspection age t j , as the equipment replacement standard.

[0051]

[0052] Compared with the prior art, the beneficial effects of the present invention are that it solves the economic waste caused by replacing equipment based on the service life of the equipment, takes into account the impact of evaluation errors on equipment replacement standards, improves the rationality and accuracy of equipment replacement standards, and significantly improves the service life of electrical equipment and the economic benefits of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0054] The present invention will be further explained below in conjunction with specific embodiments and accompanying drawings:

[0055] like Figure 1 As shown, the present invention is a method for determining the replacement standard of electrical equipment considering the evaluation error, which specifically includes the following steps:

[0056] 1) Based on the historical data of electrical equipment operation and maintenance and related experimental statistical results, establish the failure probability distribution curve g(l) of the equipment as the equipment status parameter l changes and the distribution probability curve Q of the equipment status parameter l in the kth year of use k(l), and calculate the equipment failure probability distribution curve fl(k) in the kth year.

[0057] The step 1) comprises the following steps:

[0058] 1.1) According to the equipment failure history data, the failure probability distribution curve g(l) of the equipment state parameter l is obtained, as shown in Formula 1:

[0059]

[0060] Where: l is the equipment state parameter, g(l) is the failure probability distribution curve of the equipment with parameter l.

[0061] 1.2) Based on the historical data of equipment operation and maintenance, the distribution probability curve Q of the equipment status parameter l in the kth year of use is calculated using normal distribution fitting k (l), and obtain the probability density distribution function matrix Q(x) of equipment aging parameters:

[0062]

[0063] Where: Q k (x) is the probability density distribution function of the equipment status parameter l in the kth year, which can be obtained through the historical operation and maintenance data of the equipment.

[0064] 1.3) Calculate the equipment failure probability distribution curve fl(k) in the kth year according to formula 3.

[0065]

[0066] Where: fl(k) is the equipment failure probability distribution curve in the kth year of use, Q k (l) is the distribution probability curve of the equipment state parameter l in the kth year of use, g(l) is the failure probability distribution curve of the equipment as the state parameter l changes, l max and l min are the maximum and minimum values ​​of the device state parameter l respectively.

[0067] 2) Through a large number of experiments, the state parameters of electrical equipment l are obtained real The true value and evaluation value l estimation The average error between The real l of the device status parameter real is the expected value, the average error is the standard deviation, and the evaluation parameter l is obtained estimation Distribution probability curve h(l estimation ), as shown in Formula 4.

[0068]

[0069] Among them: estimation is the evaluation value of the device status parameter, l real is the true value of the device state parameter, h(l estimation ) is the parameter l estimation The distribution probability curve of .

[0070] 3) When the parameter evaluation value is less than l c When the device is replaced, the actual value of the device status parameter is calculated according to Formula 5. r When the device is replaced, the probability r(l r ).

[0071]

[0072] Where: r(l r ) is the true value of the device state parameter l r The probability of being replaced when the device is replaced, h(l) is the distribution probability curve of the device state parameter evaluation value, l c The replacement standard for electrical equipment is that the equipment status parameter evaluation value is less than l c The device is replaced.

[0073] 4) The probability of replacing the equipment in the kth year of operation is that the equipment status parameter evaluation value is less than the replacement standard l c The probability of is as shown in Formula 6:

[0074]

[0075] Where: re(k) is the probability of replacing a device that has been in operation for k years, r(l) is the probability of replacing a device when the true value of the device parameter is l, Q k (l) is the distribution probability curve of equipment parameter l in the kth year of use, and fl(k) is the equipment failure probability distribution curve in the kth year.

[0076] 5) Establish a calculation model, input the calculation model parameters, the total number of devices N, the calculation cycle n, and obtain the replaced device matrix Failed Device Matrix and testing equipment matrix The step 5) comprises the following steps:

[0077] 5.1) Establish a device collection matrix Replaced Device Matrix Failed Device Matrix Testing equipment matrix

[0078]

[0079] Where: NA jkis the number of equipment that has been running for k years in the jth year, 1≤j≤n, 1≤k≤j.

[0080]

[0081] Where: NF jk is the number of failed equipment that has been in service for k years in the jth year, 1≤j≤n, 1≤k≤j.

[0082]

[0083] Among them: NR jk is the number of replaced equipment that has been in service for k years in the jth year, 1≤j≤n, 1≤k≤j.

[0084]

[0085] Of which: ND jk is the number of testing equipment that has been in service for k years in the jth year, 1≤j≤n, 1≤k≤j.

[0086] 5.2) Calculate the number of equipment replaced in year j that has been used for k years NR jk and the number of failures NF jk , update the replaced and failed device matrix and Calculate the number of devices that have been used for k+1 years in year j+1. j+1,k+1 .

[0087] The number of devices replaced each year is calculated as:

[0088] NR j,k =NA j,k *re(k) (Formula 11)

[0089] Among them: NR j,k is the number of equipment replaced in year j after being used for k years, NA j,k is the number of devices that have been in use for k years in the jth year, and re(k) is the probability that a device that has been in use for k years will be replaced.

[0090] The number of failed devices each year is calculated as:

[0091] NF j,k =NA j,k *fl(k) Formula 12) Where: NF j,k is the number of equipment failures in the jth year after use for k years, NA j,k is the number of devices with a service life of k years in the jth year, and fl(k) is the probability of failure of a device that has been in operation for k years.

[0092] The number of new equipment invested in year j+1 is calculated as:

[0093]

[0094] Where: NA j+1，1 is the number of new equipment invested in year j+1, NF j,k is the number of equipment failures in year j after use for k years, NR j,k is the number of equipment replaced in year j that has been used for k years.

[0095] Calculate the number of devices that have been used for k+1 years in year j+1

[0096] NA j+1,k+1 =NA j,k -NF j,k -NR j,k (Formula 14)

[0097] Where: NA j+1,k+1 is the number of devices used in year k+1 in year j+1, NA j,k is the number of devices used for k years in year j, NF j,k is the number of equipment failures in year j after use for k years, NR j,k is the number of equipment replaced in year j that has been used for k years.

[0098] 6) Input the equipment unit failure cost FC, unit replacement cost RC, unit inspection cost DC and annualized interest rate η, and calculate the life cycle cost LCC.

[0099] 6.1) Calculate the annual cost of handling equipment failures as follows:

[0100]

[0101] Where: C TFC is the total cost of handling equipment failures, FC is the cost of maintaining a single failed device, and NF j,k is the number of equipment failures in the jth year after k years of use, and η is the annualized interest rate.

[0102] 6.2) Calculate the annual cost of replacing equipment as:

[0103]

[0104] Where: C TRC is the total cost of equipment replacement, RC is the cost of replacing a single device, NR j,k is the number of equipment replaced in the jth year after being used for k years, and η is the annualized interest rate.

[0105] 6.3) Starting from t, the equipment is tested every year. The number of tested equipment each year is calculated as:

[0106]

[0107] The total testing cost is calculated as:

[0108]

[0109] Where: C TRC is the total cost of equipment testing, DC is the cost of testing a single device, and ND j,k is the number of equipment inspections in year j with k years of use, and η is the annualized interest rate.

[0110] 6.4) Based on the results obtained in step 6.1), step 6.2) and step 6.3), output the full life cycle cost as shown in formula 16:

[0111] LCC lc,t =C TIC +C TRC +C TFC +C TDC (Formula 19)

[0112] Where: C TIC C is the initial investment cost of power equipment during the calculation period; TRC is the total replacement cost of power equipment within the calculation period; C TFC is the total failure cost of power equipment within the calculation period; C TDC The total inspection cost of power equipment during the calculation period; LCC lc,t It is the total life cycle cost of the equipment replacement strategy based on condition assessment.

[0113] 7) Change optimization parameters l c and the initial inspection age t, the full life cycle cost under different replacement standards and inspection times is obtained As shown in formula 20, select the parameter l that minimizes the total life cycle cost. ci and equipment initial inspection age t j As replacement standard.

[0114]

[0115] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for determining replacement criteria for electrical equipment taking into account evaluation errors, characterized in that: The steps include: 1) Based on the historical data of electrical equipment operation and maintenance and experimental statistical results, establish the failure probability distribution curve g(l) of the equipment as the equipment status parameter l changes and the distribution probability curve Q of the equipment status parameter l in the kth year of use k (l), and calculate the equipment failure probability distribution curve fl(k) in the kth year; The step 1) comprises the following steps: 1.1) Based on the equipment failure history data, calculate the failure probability distribution curve g(l) of the equipment state quantity l; 1.2) According to the historical data of equipment operation and maintenance, the distribution probability curve Q of the equipment status parameter l in the kth year is fitted and calculated k (l); 1.3) Calculate the equipment failure probability distribution curve fl(k) in the kth year; Where: fl(k) is the equipment failure probability distribution curve in the kth year of use, Q k (l) is the distribution probability curve of the equipment state parameter l in the kth year of use, g(l) is the failure probability distribution curve of the equipment as the state parameter l changes, l max and l min are the maximum and minimum values ​​of the device state parameter l respectively; 2) Through experiments, the true value of the equipment state parameter l is obtained real and the evaluation value l estimation The balance between Mean error , with the real value of the device state parameter l real is the expected value, the average error is the standard deviation, and the evaluation parameter l is obtained estimation Distribution probability curve h(l estimation ); as shown below; Among them: estimation is the evaluation value of the device status parameter, l real is the true value of the device state parameter, h(l estimation ) is the parameter l estimation The distribution probability curve of 3) When the parameter evaluation value is less than l c When the device is replaced, the actual value of the device state parameter is calculated to be l r When the device is replaced, the probability r(l r ); Where: r(l r ) is the true value of the device state parameter l r The probability of being replaced when r ) is the true value of the device state parameter l r Distribution curve of evaluation value, l c The equipment is replaced when the equipment status parameter evaluation value is less than l c When replaced, l min is the minimum value of the state parameter l; 4) Calculate the probability of replacing the equipment in the kth year of operation as the probability that the equipment status parameter evaluation value is less than the equipment replacement standard l c probability; Where: re(k) is the probability of replacing a device that has been in operation for k years; 5) Establish a calculation model, input the calculation model parameters, the total number of devices N, the calculation cycle n, and obtain the replaced device matrix Failed Device Matrix and testing equipment matrix The step 5) comprises the following steps: 5.1) Establish a device collection matrix Replaced Device Matrix Failed Device Matrix and testing equipment matrix The above matrices are all n-order matrices; 5.2) Calculate the number of equipment replaced in year j that has been used for k years NR j,k and the number of failures NF j,k , update the replaced device matrix and failed device matrix Calculate the number of devices that have been used for k+1 years in year j+1. j+1,k+1 ; The number of devices replaced each year is calculated as: NR j,k =NA j,k *re(k) (Official 4) Among them: NR j,k is the number of equipment replaced in year j after being used for k years, NA j,k is the number of devices with a usage period of k years in year j; The number of failed devices each year is calculated as: NF j,k =NA j,k *fl(k) (Formula 5) Where: NF j,k is the number of equipment failures in the jth year after k years of use; The number of new equipment invested in year j+1 is calculated as: Among them: NA j+1,1 is the number of new equipment invested in year j+1, NR j,k is the number of equipment that has been used for k years and replaced in year j; Calculate the number of devices that have been used for k+1 years in year j+1. j+1,k+1 NA j+1,k+1 =NA j,k -NF j,k -NR j,k (Formula 7) Among them: NA j+1,k+1 is the number of devices used in year k+1 in year j+1; 6) Input the equipment unit failure cost FC, unit replacement cost RC, unit inspection cost DC and annualized interest rate η to calculate the life cycle cost LCC; 6.1) Calculate the total cost C required to handle equipment failure TFC for: Where: C TFC is the total cost of handling equipment failures, FC is the cost of maintaining a single failed device, and NF j,k is the number of equipment failures in the jth year after k years of use, and η is the annualized interest rate; 6.2) Calculate the total cost C required to replace the equipment TRC for: Where: C TRC is the total cost of replacing the equipment, NR j,k is the number of equipment that has been used for k years and is replaced in year j, and RC is the cost required to replace a single equipment; 6.3) Starting from t, the equipment is tested every year. The number of tested equipment each year is calculated as: Calculate the total testing cost C TDC for: Where: C TDC is the total equipment inspection cost within the calculation period, DC is the cost required to inspect a single device, and ND j,k is the number of equipment inspections in the jth year with k years of operation; 6.4) Based on the results obtained in step 6.1), step 6.2) and step 6.3), output the full life cycle cost: LCC lc,t =C TIC +C TRC +C TFC +C TDC (Formula 12) Where: C TIC is the initial investment cost of the equipment during the calculation period, LCC lc,t The standard for equipment replacement is l c , the full life cycle cost of the equipment when the first inspection time is t; 7) Calculate the life cycle cost under different equipment replacement standards and initial inspection years to obtain the life cycle cost matrix Get the replacement standard with the lowest life cycle cost ci and equipment initial inspection age t j , as the equipment replacement standard:

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