Low-voltage line fault diagnosis and analysis method and device

Abstract

The invention provides a low-voltage line fault diagnosis and analysis method which comprises the following steps: when a low-voltage line has a fault, acquiring an abrupt change current waveform sensed by a secondary side of a current transformer, and correcting the acquired abrupt change current waveform; determining preset fault current waveforms corresponding to the plurality of fault types, and performing synchronous sampling on the corrected abrupt change current waveform and all fault current waveforms according to a specified sampling interval; and performing deviation goodness of fit and mean square error goodness of fit calculation on the corrected sampling data of the abrupt change current waveform and the sampling data of each fault current waveform, and determining a fault type corresponding to the low-voltage line from the plurality of fault types according to a calculation result. By implementing the method, line fault data capturing on the low-voltage distribution network line is realized, fault wave data is analyzed, and a fault diagnosis analysis result is quickly given.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a method and device for diagnosing and analyzing a low-voltage line fault. Background Art

[0002] At present, the operating environment of the low-voltage distribution network is relatively complex, especially in old residential areas where there are aging lines, obsolete equipment, and a large number of switch models. The lines are prone to short-circuit tripping or switch electrical fault tripping. Most of the switches installed in old residential areas do not have fault current detection functions. Once a fault occurs, the distribution network line repair personnel need to check the insulation performance of the line by shaking the meter, etc., but it is often difficult to find the fault point. However, given the premise that the fault point cannot be determined in a short period of time and the power supply to residents needs to be restored as soon as possible, the distribution network line repair personnel can only re-close the switch and power on, but re-closing the switch and powering on only delays the fault problem, which is likely to cause a secondary power outage and increase the workload of line repair.

[0003] With the improvement of the quality of life, people have put forward higher requirements for power supply reliability, and therefore also put forward requirements for distribution network line repair personnel to quickly locate and repair power supply line faults. However, the existing technology still lacks a method for capturing line fault data on low-voltage distribution network lines, analyzing fault wave data, and quickly providing fault diagnosis and analysis results. Summary of the invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide a low-voltage line fault diagnosis and analysis method and device, which can realize line fault data capture, analyze fault wave data on a low-voltage distribution network line, and quickly provide fault diagnosis and analysis results.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a low-voltage line fault diagnosis and analysis method, the method comprising the following steps:

[0006] When a fault occurs in the low voltage line, the sudden current waveform sensed by the secondary side of the current transformer is obtained, and the obtained sudden current waveform is corrected;

[0007] Determine the preset fault current waveforms corresponding to each of the multiple fault types, and synchronously sample the corrected mutation current waveform and all the fault current waveforms according to the specified sampling interval;

[0008] The deviation fit and mean square error fit of the corrected sampling data of the mutation current waveform are calculated respectively with the sampling data of each fault current waveform, and the fault type corresponding to the low-voltage line is determined from the multiple fault types according to the calculation results.

[0009] Wherein, the obtained sudden change current waveform is corrected by a built-in three-point smoothing algorithm.

[0010] Among them, the expression of the three-point smoothing algorithm is F t =aU t-1 +bU t +cU t+1 ;in,

[0011] F t is the smoothed data at time t; U t is the actual measured value at time t; U t-1 is the actual measured value at time t-1; U t+1 is the actual measured value at time t+1; a, b and c are constants with values ​​between [0,1].

[0012] The step of calculating the deviation fit and mean square error fit of the sampled data of the corrected mutation current waveform and the sampled data of each fault current waveform, and determining the fault type corresponding to the low-voltage line from the multiple fault types according to the calculation results specifically includes:

[0013] By formula Calculate the deviation agreement ΔX between the sampling data of the modified mutation current waveform and the sampling data of each fault current waveform; where P i is the i-th sampling data of the corrected mutation current waveform; θ ji is the i-th sampling data after the j-th fault current waveform is amplified; and is the i-th sampling data before the j-th fault current waveform is amplified, h is the maximum amplitude of the modified mutation current waveform, a is the amplitude of the j-th fault current waveform; n is the total number of sampling points set corresponding to the specified sampling interval, which is a fixed value;

[0014] By formula Calculate the mean square error agreement ΔY between the corrected sampling data of the sudden current waveform and the sampling data of each fault current waveform;

[0015] All calculated mean square error fits are sorted and numbered in ascending order, and each fault current waveform is assigned a corresponding number according to the sorted mean square error fit; wherein the number of each fault current waveform is the number of its corresponding mean square error fit after sorting;

[0016] According to the calculated deviation matching degree, from all the fault current waveforms assigned with numbers, the fault current waveform with the corresponding deviation matching degree less than the preset threshold and the smallest number is screened out, and further according to the selected fault current waveform, the corresponding fault type is determined as the fault type corresponding to the low-voltage line and output.

[0017] Wherein, the method further comprises:

[0018] If the calculated deviation matching degrees are all greater than the preset threshold, an alarm message is output.

[0019] Among them, the fault types include ground short circuit fault, phase-to-phase short circuit fault, animal limb phase-to-phase short circuit fault, water intrusion short circuit fault and non-short circuit tripping fault.

[0020] The embodiment of the present invention further provides a low-voltage line fault diagnosis and analysis device, comprising:

[0021] The fault current waveform acquisition and correction unit is used to obtain the sudden change current waveform sensed by the secondary side of the current transformer when a fault occurs in the low-voltage line, and to correct the obtained sudden change current waveform;

[0022] A current waveform synchronous sampling unit is used to determine the preset fault current waveforms corresponding to each of the multiple fault types, and synchronously sample the corrected mutation current waveform and all fault current waveforms according to a specified sampling interval;

[0023] The fault type diagnosis and analysis unit is used to calculate the deviation consistency and mean square error consistency of the sampled data of the corrected mutation current waveform and the sampled data of each fault current waveform, and determine the fault type corresponding to the low-voltage line from the multiple fault types based on the calculation results.

[0024] Wherein, the fault type diagnosis and analysis unit includes:

[0025] Deviation fit calculation module, used to calculate the deviation fit through the formula Calculate the deviation agreement ΔX between the sampling data of the modified mutation current waveform and the sampling data of each fault current waveform; where P i is the i-th sampling data of the corrected mutation current waveform; θ ji is the i-th sampling data after the j-th fault current waveform is amplified; and is the i-th sampling data before the j-th fault current waveform is amplified, h is the maximum amplitude of the modified mutation current waveform, a is the amplitude of the j-th fault current waveform; n is the total number of sampling points set corresponding to the specified sampling interval, which is a fixed value;

[0026] The mean square error goodness of fit calculation module is used to calculate the mean square error goodness of fit through the formula Calculate the mean square error agreement ΔY between the corrected sampling data of the sudden current waveform and the sampling data of each fault current waveform;

[0027] The sorting and coding module is used to sort and number all calculated mean square error fits in ascending order, and assign a corresponding number to each fault current waveform according to the sorted mean square error fit; wherein the number of each fault current waveform is the number of its corresponding mean square error fit after sorting;

[0028] The fault diagnosis and analysis module is used to screen out the fault current waveform with the corresponding deviation matching degree less than a preset threshold and the smallest number from all the fault current waveforms assigned numbers according to the calculated deviation matching degree, and further determine the corresponding fault type as the fault type corresponding to the low-voltage line according to the selected fault current waveform and output it.

[0029] Among them, the fault types include ground short circuit fault, phase-to-phase short circuit fault, animal limb phase-to-phase short circuit fault, water intrusion short circuit fault and non-short circuit tripping fault.

[0030] The obtained sudden current waveform is corrected by a built-in three-point smoothing algorithm;

[0031] The expression of the three-point smoothing algorithm is F t =aU t-1 +bU t +cU t+1 Among them, F t is the smoothed data at time t; U t is the actual measured value at time t; U t-1 is the actual measured value at time t-1; U t+1 is the actual measured value at time t+1; a, b and c are constants with values ​​between [0,1].

[0032] Implementing the embodiments of the present invention has the following beneficial effects:

[0033] When a fault occurs in a low-voltage line, the present invention determines the fault type of the low-voltage line by calculating the deviation fit and the mean square error fit based on the sudden change current waveform sensed by the secondary side of the current transformer and in combination with preset fault current waveforms corresponding to a plurality of fault types, thereby enabling line fault data capture and fault wave data analysis on the low-voltage distribution network line, and quickly providing fault diagnosis analysis results. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0035] Figure 1 A flowchart of a low-voltage line fault diagnosis and analysis method provided by an embodiment of the present invention;

[0036] Figure 2 A schematic structural diagram of a low-voltage line fault diagnosis and analysis device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0038] like Figure 1 As shown in the figure, a low voltage line fault diagnosis and analysis method proposed by the inventor in an embodiment of the present invention comprises the following steps:

[0039] Step S1, when a fault occurs in the low voltage line, a sudden change current waveform sensed by the secondary side of the current transformer is obtained, and the obtained sudden change current waveform is corrected;

[0040] Step S2, determining a preset fault current waveform corresponding to each of the multiple fault types, and synchronously sampling the corrected mutation current waveform and all the fault current waveforms according to a specified sampling interval;

[0041] Step S3, calculating the deviation fit and mean square error fit of the corrected sampling data of the sudden current waveform and the sampling data of each fault current waveform, and determining the fault type corresponding to the low-voltage line from the multiple fault types according to the calculation results.

[0042] The specific process is that in step S1, when a fault occurs in the low-voltage line, the secondary side of the current transformer will sense a sudden current waveform, and once the sudden peak value of the sudden current waveform exceeds the set threshold value, it will be triggered for collection.

[0043] At this time, considering that the sudden current waveform has occasional single jump data, the obtained sudden current waveform can be corrected by a three-point smoothing algorithm. Among them, the three-point algorithm is a weighted average method, and its corresponding expression is F t =aU t-1 +bU t +cU t+1 ;

[0044] Among them, F t is the smoothed data at time t; U t is the actual measured value at time t; U t-1 is the actual measured value at time t-1; U t+1 is the actual measured value at time t+1; a, b and c are constants with values ​​between [0,1], for example, a and c are 0.2 and b is 0.6.

[0045] In step S2, first, it is determined that there are multiple built-in fault types, including but not limited to ground short circuit fault, phase-to-phase short circuit fault, animal limb phase-to-phase short circuit fault, water intrusion short circuit fault and non-short circuit tripping fault.

[0046] Secondly, a corresponding fault current waveform is introduced for each fault type, so that the fault type of the low-voltage line can be determined based on the sudden change current waveform.

[0047] Finally, according to the specified sampling interval, the modified mutation current waveform and all fault current waveforms are synchronously sampled. For example, if a complete sequence of 128 points of AC waveform data is required, the total continuous acquisition time is 20mS, that is, the sampling interval is set to 20mS / 128. Here, the sampled data of the modified mutation current waveform is represented as P i , the sampling data of the jth fault current waveform is expressed as Wherein, i=1,…,128; j=1,…,m; m is the total number of fault types.

[0048] In step S3, the deviation and mean square error are used to evaluate the waveform fit. Among them, the deviation refers to the degree of data deviation, which is the average value of the difference between each data and its expected value. The larger the deviation, the greater the degree of deviation of the data from the expected value, and vice versa. The mean square error (MSE) refers to the degree of discreteness of the data distribution, which is the average value of the sum of the squares of the difference between each data and its reference model data. The larger the mean square error, the greater the degree of data dispersion, and vice versa. The difference between the mean square error and the deviation is that the influence of the positive and negative deviations offsetting each other can be eliminated, and the numerical value can be used directly to judge the quality. Obviously, the smaller the mean square error, the better.

[0049] Therefore, first, by the formula Calculate the deviation agreement ΔX between the sampling data of the modified mutation current waveform and the sampling data of each fault current waveform; where P i is the i-th sampling data of the corrected mutation current waveform; θ ji is the i-th sampling data after the j-th fault current waveform is amplified; and is the i-th sampling data before the j-th fault current waveform is amplified, h is the maximum amplitude of the corrected mutation current waveform, a is the amplitude of the j-th fault current waveform; n is the total number of sampling points set based on the specified sampling interval, which is a fixed value.

[0050] It should be noted that in order to obtain the best comparison effect, considering that the amplitude of the modified mutation current waveform is greatly different from the amplitude of each fault current waveform, the deviation fit calculation is performed after the same-year scaling process. For example, if the maximum amplitude of the modified mutation current waveform is h, and the amplitude of the fault current waveform is a, the amplitude of the fault current waveform is amplified by h / a times.

[0051] Secondly, through the formula The mean square error agreement ΔY between the corrected sampling data of the sudden current waveform and the sampling data of each fault current waveform is calculated.

[0052] Then, all calculated mean square error fits are sorted and numbered in ascending order, and each fault current waveform is assigned a corresponding number according to the sorted mean square error fit; wherein, the number of each fault current waveform is the number of its corresponding mean square error fit after sorting.

[0053] Finally, according to the calculated deviation matching degree, the fault current waveform with the smallest number and the corresponding deviation matching degree less than the preset threshold is screened out from all the fault current waveforms assigned numbers, and further according to the selected fault current waveform, the corresponding fault type is determined as the fault type corresponding to the low-voltage line and output.

[0054] In one example, a plurality of fault types are pre-stored, including a short circuit to ground fault, a phase-to-phase short circuit fault, an animal limb phase-to-phase short circuit fault, a water intrusion short circuit fault, and a non-short circuit trip fault.

[0055] At this time, according to the deviation consistency between the sampling data of the sudden current waveform and the sampling data of all the above-mentioned fault current waveforms, the fault current waveforms whose deviation consistency is less than the preset threshold are screened, so as to retain the fault types that meet the above requirements, specifically, short-circuit faults to ground, short-circuit faults between phases and non-short-circuit tripping faults.

[0056] Next, according to the mean square error match between the sampling data of the corrected mutation current waveform and the sampling data of each fault current waveform, the above-retained short-circuit faults to ground, phase-to-phase short-circuit faults and non-short-circuit tripping faults are numbered and sorted, and the fault types are obtained with numbers arranged in order from small to large: phase-to-phase short-circuit fault -> short-circuit fault to ground -> non-short-circuit tripping fault.

[0057] Finally, the interphase short circuit fault with the smallest number is selected as the fault type corresponding to the low-voltage line and output.

[0058] In an embodiment of the present invention, the method further includes: if the calculated deviation matching degrees are greater than a preset threshold, an alarm message is output, so that an alarm can be issued when the fault type cannot be determined, so that subsequent investigation and repair can be carried out in time by distribution network line repair personnel.

[0059] like Figure 2 As shown in the figure, a low voltage line fault diagnosis and analysis device is provided in an embodiment of the present invention, comprising:

[0060] The fault current waveform acquisition and correction unit 110 is used to obtain the sudden change current waveform sensed by the secondary side of the current transformer when a fault occurs in the low-voltage line, and to correct the obtained sudden change current waveform;

[0061] The current waveform synchronous sampling unit 120 is used to determine the preset fault current waveforms corresponding to the multiple fault types, and synchronously sample the corrected mutation current waveform and all the fault current waveforms according to the specified sampling interval;

[0062] The fault type diagnosis and analysis unit 130 is used to calculate the deviation consistency and mean square error consistency of the corrected mutation current waveform sampling data and the sampling data of each fault current waveform, and determine the fault type corresponding to the low-voltage line from the multiple fault types according to the calculation results.

[0063] Wherein, the fault type diagnosis and analysis unit 130 includes:

[0064] Deviation fit calculation module, used to calculate the deviation fit through the formula Calculate the deviation agreement ΔX between the sampling data of the modified mutation current waveform and the sampling data of each fault current waveform; where P i is the i-th sampling data of the corrected mutation current waveform; θ ji is the i-th sampling data after the j-th fault current waveform is amplified; and is the i-th sampling data before the j-th fault current waveform is amplified, h is the maximum amplitude of the modified mutation current waveform, a is the amplitude of the j-th fault current waveform; n is the total number of sampling points set corresponding to the specified sampling interval, which is a fixed value;

[0065] The mean square error goodness of fit calculation module is used to calculate the mean square error goodness of fit through the formula Calculate the mean square error agreement ΔY between the corrected sampling data of the sudden current waveform and the sampling data of each fault current waveform;

[0066] The sorting and coding module is used to sort and number all calculated mean square error fits in ascending order, and assign a corresponding number to each fault current waveform according to the sorted mean square error fit; wherein the number of each fault current waveform is the number of its corresponding mean square error fit after sorting;

[0067] The fault diagnosis and analysis module is used to screen out the fault current waveform with the corresponding deviation matching degree less than a preset threshold and the smallest number from all the fault current waveforms assigned numbers according to the calculated deviation matching degree, and further determine the corresponding fault type as the fault type corresponding to the low-voltage line according to the selected fault current waveform and output it.

[0068] Among them, the fault types include ground short circuit fault, phase-to-phase short circuit fault, animal limb phase-to-phase short circuit fault, water intrusion short circuit fault and non-short circuit tripping fault.

[0069] The obtained sudden current waveform is corrected by a built-in three-point smoothing algorithm;

[0070] The expression of the three-point smoothing algorithm is F t =aU t-1 +bU t +cU t+1 ; Among them, F t is the smoothed data at time t; U t is the actual measured value at time t; U t-1 is the actual measured value at time t-1; U t+1 is the actual measured value at time t+1; a, b and c are constants with values ​​between [0,1].

[0071] Implementing the embodiments of the present invention has the following beneficial effects:

[0072] When a fault occurs in a low-voltage line, the present invention determines the fault type of the low-voltage line by calculating the deviation fit and the mean square error fit based on the sudden change current waveform sensed by the secondary side of the current transformer and in combination with preset fault current waveforms corresponding to a plurality of fault types, thereby enabling line fault data capture and fault wave data analysis on the low-voltage distribution network line, and quickly providing fault diagnosis analysis results.

[0073] It is worth noting that in the above-mentioned device embodiment, the various device modules included are only divided according to functional logic, but are not limited to the above-mentioned division, as long as the corresponding functions can be realized; in addition, the specific names of the various functional modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention.

[0074] A person skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, CD-ROM, etc.

[0075] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A low voltage line fault diagnosis and analysis method, characterized in that: The method comprises the following steps: When a fault occurs in the low voltage line, the sudden current waveform sensed by the secondary side of the current transformer is obtained, and the obtained sudden current waveform is corrected; Determine the preset fault current waveforms corresponding to each of the multiple fault types, and synchronously sample the corrected mutation current waveform and all the fault current waveforms according to the specified sampling interval; The deviation fit and mean square error fit of the corrected sampling data of the mutation current waveform are calculated respectively with the sampling data of each fault current waveform, and the fault type corresponding to the low-voltage line is determined from the multiple fault types according to the calculation results.

2. The low voltage line fault diagnosis and analysis method according to claim 1, characterized in that: The obtained sudden current waveform is corrected by a built-in three-point smoothing algorithm.

3. The low voltage line fault diagnosis and analysis method according to claim 2, characterized in that: The expression of the three-point smoothing algorithm is F t =aU t-1 +bU t +cU t+1 ;in, F t is the smoothed data at time t; U t is the actual measured value at time t; U t-1 is the actual measured value at time t-1; U t+1 is the actual measured value at time t+1; a, b and c are constants with values ​​between [0,1].

4. The low voltage line fault diagnosis and analysis method according to claim 1, characterized in that: The step of calculating the deviation fit and mean square error fit of the corrected sampling data of the mutation current waveform and the sampling data of each fault current waveform, and determining the fault type corresponding to the low-voltage line from the multiple fault types according to the calculation results specifically includes: By formula Calculate the deviation agreement ΔX between the sampling data of the modified mutation current waveform and the sampling data of each fault current waveform; where P i is the i-th sampling data of the corrected mutation current waveform; θ ji is the i-th sampling data after the j-th fault current waveform is amplified; and is the i-th sampling data before the j-th fault current waveform is amplified, h is the maximum amplitude of the modified mutation current waveform, a is the amplitude of the j-th fault current waveform; n is the total number of sampling points set corresponding to the specified sampling interval, which is a fixed value; By formula Calculate the mean square error agreement ΔY between the corrected sampling data of the sudden current waveform and the sampling data of each fault current waveform; All calculated mean square error fits are sorted and numbered in ascending order, and each fault current waveform is assigned a corresponding number according to the sorted mean square error fit; wherein the number of each fault current waveform is the number of its corresponding mean square error fit after sorting; According to the calculated deviation matching degree, from all the fault current waveforms assigned with numbers, the fault current waveform with the corresponding deviation matching degree less than the preset threshold and the smallest number is screened out, and further according to the selected fault current waveform, the corresponding fault type is determined as the fault type corresponding to the low-voltage line and output.

5. The low voltage line fault diagnosis and analysis method according to claim 4, characterized in that: The method further comprises: If the calculated deviation matching degrees are all greater than the preset threshold, an alarm message is output.

6. The low voltage line fault diagnosis and analysis method according to claim 4, characterized in that: The fault types include short circuit to ground fault, phase-to-phase short circuit fault, animal limb phase-to-phase short circuit fault, water intrusion short circuit fault and non-short circuit trip fault.

7. A low voltage line fault diagnosis and analysis device, characterized in that: include: The fault current waveform acquisition and correction unit is used to obtain the sudden change current waveform sensed by the secondary side of the current transformer when a fault occurs in the low-voltage line, and to correct the obtained sudden change current waveform; A current waveform synchronous sampling unit is used to determine the preset fault current waveforms corresponding to each of the multiple fault types, and synchronously sample the corrected mutation current waveform and all fault current waveforms according to a specified sampling interval; The fault type diagnosis and analysis unit is used to calculate the deviation consistency and mean square error consistency of the sampled data of the corrected mutation current waveform and the sampled data of each fault current waveform, and determine the fault type corresponding to the low-voltage line from the multiple fault types based on the calculation results.

8. The low voltage line fault diagnosis and analysis device according to claim 7, characterized in that: The fault type diagnosis and analysis unit comprises: Deviation fit calculation module, used to calculate the deviation fit through the formula Calculate the deviation agreement ΔX between the sampling data of the modified mutation current waveform and the sampling data of each fault current waveform; where P i is the i-th sampling data of the corrected mutation current waveform; θ ji is the i-th sampling data after the j-th fault current waveform is amplified; and is the i-th sampling data before the j-th fault current waveform is amplified, h is the maximum amplitude of the modified mutation current waveform, a is the amplitude of the j-th fault current waveform; n is the total number of sampling points set corresponding to the specified sampling interval, which is a fixed value; The mean square error goodness of fit calculation module is used to calculate the mean square error goodness of fit through the formula Calculate the mean square error agreement ΔY between the corrected sampling data of the sudden current waveform and the sampling data of each fault current waveform; The sorting and coding module is used to sort and number all calculated mean square error fits in ascending order, and assign a corresponding number to each fault current waveform according to the sorted mean square error fit; wherein the number of each fault current waveform is the number of its corresponding mean square error fit after sorting; The fault diagnosis and analysis module is used to screen out the fault current waveform with the corresponding deviation matching degree less than a preset threshold and the smallest number from all the fault current waveforms assigned numbers according to the calculated deviation matching degree, and further determine the corresponding fault type as the fault type corresponding to the low-voltage line according to the selected fault current waveform and output it.

9. The low voltage line fault diagnosis and analysis device according to claim 8, characterized in that: The fault types include short circuit to ground fault, phase-to-phase short circuit fault, animal limb phase-to-phase short circuit fault, water intrusion short circuit fault and non-short circuit trip fault.

10. The low voltage line fault diagnosis and analysis device according to claim 7, characterized in that: The obtained sudden current waveform is corrected by a built-in three-point smoothing algorithm; wherein, The expression of the three-point smoothing algorithm is F t =aU t-1 +bU t +cU t+1 Among them, F t is the smoothed data at time t; U t is the actual measured value at time t; U t-1 is the actual measured value at time t-1; U t+1 is the actual measured value at time t+1; a, b and c are constants with values ​​between [0,1].

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