A method for measuring initial error of a power transformer

Abstract

The application discloses a power transformer initial error metering method, comprising the following steps: collecting initial standard data of M groups of transformers in a same transformer substation, and calculating first proportional values between different groups of the transformers based on the initial standard data; collecting in-service monitoring data of the M groups of transformers in the same transformer substation, and calculating second proportional values of different groups of the transformers based on the in-service monitoring data and the first proportional values; constructing an equation group of initial errors of different groups of the transformers according to the second proportional values, and solving the equation group to obtain initial errors of the M groups of transformers in the same transformer substation. The application solves the problem of how to accurately and quickly meter initial errors of power transformers and output results.

Description

Technical Field

[0001] This invention relates to the field of instrument transformer technology, and in particular to a method for measuring the initial error of a power instrument transformer. Background Technology

[0002] With the construction of ultra-high voltage (UHV) transmission lines and the development of digital power systems, electromagnetic voltage transformers have become insufficient to meet the measurement and protection requirements of power systems in terms of principle and structure. Capacitive voltage transformers (CVTs) have emerged as a solution. CVTs offer numerous advantages, including simple structure, high withstand voltage levels, large insulation margin, no magnetic saturation or ferroresonance, simple operation and maintenance, good economic efficiency, and ease of live-line monitoring. After years of research and improvement, CVTs have become one of the key devices for acquiring electrical data in power systems and are widely used in high-voltage power systems with voltage levels of 110kV and above. However, CVTs also have their own drawbacks. A CVT (Continuous Voltage Transformer) mainly consists of three parts: a capacitive voltage divider, a medium-voltage transformer, and a compensating reactor. This modular design makes its error characteristics susceptible to external environmental factors such as temperature, frequency, and ambient electric field. Furthermore, problems like capacitor core breakdown and insulating oil aging in the CVT's capacitive voltage divider can cause changes in the voltage division ratio, affecting the accuracy of measurement data. In severe cases, this can even affect the accurate operation of relay protection systems, threatening the safe and stable operation of the power system. Therefore, monitoring the operating status of the CVT and performing timely maintenance to ensure its compliance with relevant regulations is crucial.

[0003] The current metrological verification standard for power transformers, JJG1021-2007 "Power Transformers," stipulates that the verification cycle for CVTs should not exceed four years. Currently, the common practice is to conduct offline periodic verification of CVTs. However, in practice, it has been found that many online CVTs cannot be shut down, otherwise it would severely impact production and residential power supply; moreover, the fixed testing cycle leads to both under-maintenance and over-maintenance issues, making it impossible to promptly grasp the actual operating status of the CVTs; furthermore, the error characteristics of CVTs are easily affected by environmental factors, and the error data obtained from offline verification according to the verification standard inevitably deviates from the actual operating environment due to the difference between the CVT's operating environment and its actual operating conditions. In other words, offline error data cannot fully reflect the error characteristics of the CVT in actual operation. To address the problems of offline periodic verification, domestic and international scholars have conducted research on how to conduct online real-time monitoring of CVTs, mainly including: methods based on physical model analysis, methods based on signal processing, data-driven methods, and methods and corresponding algorithms based on data-knowledge fusion. However, these methods and corresponding algorithms all assume that the monitored CVT is error-free in the initial stage of the monitoring process. Thus, changes in the monitoring data can be used to determine the CVT's operating status. However, if the CVT has initial errors, these monitoring methods and algorithms may misjudge the situation. For example, if the CVT has a positive initial error that disappears at time t0, the monitoring methods and algorithms might incorrectly determine that the CVT has a reverse deviation at time t0, leading to a misjudgment. Summary of the Invention

[0004] The main objective of this invention is to provide a method for measuring the initial error of a power transformer, aiming to solve the problem of how to accurately and quickly measure the initial error of a power transformer and output the results.

[0005] To achieve the above objectives, the present invention provides a method for measuring the initial error of a power transformer, comprising the following steps:

[0006] S1. Collect the initial standard data of M groups of instrument transformers in the same substation, and calculate the first ratio value between the initial standard data of different groups of in-phase instrument transformers based on the initial standard data.

[0007] S2. Collect the in-operation monitoring data of M groups of instrument transformers in the same substation, and calculate the second ratio value of the in-operation monitoring data of different groups of instrument transformers based on the in-operation monitoring data and the first ratio value.

[0008] S3. Construct a set of equations for the initial errors of different groups of current transformers in phase based on the second proportional value, and solve the set of equations to obtain the initial errors of M groups of current transformers in the same substation.

[0009] One preferred embodiment, after collecting the initial standard data of M groups of instrument transformers within the same substation in step S1, further includes:

[0010] The initial standard data is divided according to phase, with each phase grouped into a measurement unit. The first measurement unit is denoted as:

[0011] X = {X1, X2, ..., X} M}

[0012] Where X is the first unit of measurement, X M This is the in-phase dataset in the initial standard data of the Mth current transformer, where M is the number of current transformer groups.

[0013] One preferred embodiment is that, in step S1, calculating the first ratio value between the initial standard data of different groups of in-phase transformers specifically involves:

[0014] Selecting any channel of any current transformer as a reference, calculate the first proportional value between different groups of in-phase initial standard data of the current transformer. The first proportional value has M-1 parameters, and the first proportional value is:

[0015]

[0016] Among them, kX M1 Here is the first proportional value between the first group and the Mth group of mutual inductors, and mean() is the mean calculation function.

[0017] In one preferred embodiment, after collecting the in-operation monitoring data of M groups of instrument transformers within the same substation in step S2, the method further includes:

[0018] The in-operation monitoring data is divided by phase, with each phase grouped into a measurement unit. The second measurement unit is denoted as:

[0019] X' = ​​{X1', X2', ..., X} M '}

[0020] Where X' is the second unit of measurement, X M ' represents the in-phase dataset of the Mth current transformer in the operational monitoring data, where M is the number of current transformer groups.

[0021] In one preferred embodiment, step S2 involves calculating a second proportional value for the in-operation monitoring data of different groups of current transformers based on the in-operation monitoring data and the first proportional value, specifically as follows:

[0022] Taking any channel of any current transformer as a reference, calculate the second proportional value of the monitoring data of different groups of in-phase current transformers. The second proportional value has M parameters, and the second proportional value is:

[0023]

[0024] Among them, X” M This is the second proportional value for the Mth group of current transformers.

[0025] One preferred embodiment, step S3, specifically includes:

[0026] S31. Construct a monitoring model for each channel based on the second proportional value;

[0027] S32. The monitoring model is mathematically derived to obtain a set of equations;

[0028] S33. Within the second measurement unit, select the channel with the smallest initial error among all channels as the reference channel and set its initial error to zero.

[0029] S34. Solve the system of equations according to steps S32 and S33 to obtain the initial errors of M groups of instrument transformers in the same substation.

[0030] In one preferred embodiment, step S31 involves constructing a monitoring model for each channel based on the second proportional value, specifically as follows:

[0031] Selecting any channel of any current transformer as a reference, a monitoring model for each channel is constructed based on the second proportional value. The monitoring model is as follows:

[0032]

[0033] Among them, Y M Let L be the initial error of any channel within the same metering unit of the Mth group of current transformers, and L be the reference channel data.

[0034] One preferred approach is to derive the monitoring model mathematically:

[0035]

[0036] The Taylor series expansion of 1 / (1+Y2) is approximately equal to 1-Y2;

[0037] therefore,

[0038]

[0039] Where Y1Y2 are second-order minor quantities, the system of equations can be obtained by simplification. The system of equations is as follows:

[0040]

[0041] In one preferred embodiment, step S33, within the second metering unit, selects the channel with the smallest initial error among all channels as the reference channel and sets its initial error to zero. Specifically:

[0042] min(|Y1|,|Y2|,…|Y M |)=0

[0043] Here, min() is the minimum value function.

[0044] In one preferred embodiment, the initial standard data is measurement data that has passed installation acceptance or verification.

[0045] In the above technical solution of the present invention, the method for measuring the initial error of a power transformer includes the following steps: collecting initial standard data of M groups of transformers in the same substation, and calculating a first ratio between the initial standard data of different groups of transformers in phase based on the initial standard data; collecting in-operation monitoring data of M groups of transformers in the same substation, and calculating a second ratio between the in-operation monitoring data of different groups of transformers in phase based on the in-operation monitoring data and the first ratio; constructing a system of equations for the initial error of different groups of transformers in phase based on the second ratio, and solving the system of equations to obtain the initial error of the M groups of transformers in the same substation. The present invention solves the problem of how to accurately and quickly measure the initial error of a power transformer and output the results.

[0046] In this invention, by collecting measurement data that exceeds the tolerance, i.e., initial standard data, a proportional relationship is constructed between different groups of in-phase initial standard data, i.e., a first proportional value. The proportional relationship can eliminate the differences between different groups of monitoring data caused by factors such as transformer and line parameters in subsequent in-operation monitoring data, thereby constructing a set of equations with the initial error of the current transformer as the single unknown. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0048] Figure 1 This is a first schematic diagram of an initial error measurement method for a power transformer according to an embodiment of the present invention;

[0049] Figure 2 This is a second schematic diagram of an initial error measurement method for a power transformer according to an embodiment of the present invention;

[0050] Figure 3 This is a circuit topology diagram of a substation under an error evaluation test environment according to an embodiment of the present invention;

[0051] Figure 4This is a schematic diagram of the A-phase signal collected by a monitoring device when the four sets of capacitive voltage transformers are within tolerance, according to an embodiment of the present invention.

[0052] Figure 5 This is a schematic diagram of the A-phase signal collected by the monitoring device when the four sets of capacitive voltage transformers have initial errors according to an embodiment of the present invention;

[0053] Figure 6 This is a schematic diagram of the initial error setting values ​​for phase A of four sets of capacitive voltage transformers according to an embodiment of the present invention;

[0054] Figure 7 This is a comparison chart of the initial error setting value and the estimated value of the four sets of capacitive voltage transformers of phase A in an embodiment of the present invention.

[0055] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] It should be noted that all directional indicators (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0058] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0059] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0060] See Figure 1 According to one aspect of the present invention, the present invention provides a method for measuring the initial error of a power transformer, wherein the method for measuring the initial error of a power transformer includes the following steps:

[0061] S1. Collect the initial standard data of M groups of instrument transformers in the same substation, and calculate the first ratio value between the initial standard data of different groups of in-phase instrument transformers based on the initial standard data.

[0062] S2. Collect the in-operation monitoring data of M groups of instrument transformers in the same substation, and calculate the second ratio value of the in-operation monitoring data of different groups of instrument transformers based on the in-operation monitoring data and the first ratio value.

[0063] S3. Construct a set of equations for the initial errors of different groups of current transformers in phase based on the second proportional value, and solve the set of equations to obtain the initial errors of M groups of current transformers in the same substation.

[0064] Specifically, in this embodiment, the current transformer includes three-phase data of phase A, phase B, and phase C. The current transformer is a capacitive voltage transformer. This invention does not impose specific limitations, and the specific settings can be configured as needed. M is the number of groups of current transformers collected, and M≥2.

[0065] Specifically, in this embodiment, after collecting the initial standard data of M groups of instrument transformers within the same substation in step S1, the method further includes:

[0066] The initial standard data is divided according to phase, with each phase grouped into a measurement unit. The first measurement unit is denoted as:

[0067] X = {X1, X2, ..., X} M}

[0068] Where X is the first unit of measurement, X M This is the in-phase dataset in the initial standard data of the Mth current transformer, where M is the number of current transformer groups.

[0069] Specifically, in this embodiment, the calculation of the first ratio value between different groups of in-phase initial standard data of the current transformer in step S1 is as follows:

[0070] Selecting any channel of any current transformer as a reference, calculate the first proportional value between different groups of in-phase initial standard data of the current transformer. The first proportional value has M-1 parameters, and the first proportional value is:

[0071]

[0072] Among them, kX M1 Here is the first proportional value between the first group and the Mth group of mutual inductors, and mean() is the mean calculation function.

[0073] Specifically, in this embodiment, after collecting the in-operation monitoring data of M groups of instrument transformers within the same substation in step S2, the method further includes:

[0074] The in-operation monitoring data is divided by phase, with each phase grouped into a measurement unit. The second measurement unit is denoted as:

[0075] X' = ​​{X1', X2', ..., X} M '}

[0076] Where X' is the second unit of measurement, X M ' represents the in-phase dataset of the Mth current transformer in the operational monitoring data, where M is the number of current transformer groups.

[0077] Specifically, in this embodiment, step S2, based on the in-operation monitoring data and the first proportional value, calculates a second proportional value for the in-operation monitoring data of different groups of current transformers in phase, specifically as follows:

[0078] Taking any channel of any current transformer as a reference, calculate the second proportional value of the monitoring data of different groups of in-phase current transformers. The second proportional value has M parameters, and the second proportional value is:

[0079]

[0080] Where, X″ M This is the second proportional value for the Mth group of current transformers.

[0081] Specifically, in this embodiment, step S3 is as follows:

[0082] S31. Construct a monitoring model for each channel based on the second proportional value;

[0083] S32. The monitoring model is mathematically derived to obtain a set of equations;

[0084] S33. Within the second measurement unit, select the channel with the smallest initial error among all channels as the reference channel and set its initial error to zero.

[0085] S34. Solve the system of equations according to steps S32 and S33 to obtain the initial errors of M groups of instrument transformers in the same substation.

[0086] Specifically, in this embodiment, step S31, which constructs a monitoring model for each channel based on the second proportional value, specifically involves:

[0087] Selecting any channel of any current transformer as a reference, a monitoring model for each channel is constructed based on the second proportional value. The monitoring model is as follows:

[0088]

[0089] Among them, Y M Let L be the initial error of any channel within the same metering unit of the Mth group of current transformers, and L be the reference channel data.

[0090] Specifically, in this embodiment, the system of equations is:

[0091]

[0092] Specifically, in this embodiment, step S33 within the second metering unit selects the channel with the smallest initial error among all channels as the reference channel and sets its initial error to zero, specifically as follows:

[0093] min(|Y1|,|Y2|,…|Y M |)=0

[0094] Here, min() is the minimum value function.

[0095] Specifically, in this embodiment, the accuracy of the equation solution depends on the selection of the reference channel, including, for each sampling time, denoted as MX = mean(X″1,X″2,…,X″). M ), where MX represents the mean of the second scale value at each sampling time, mean() is the mean function, and an array Q is constructed, wherein the array Q is:

[0096] Q=[X″1-MX,X″2-MX,…,X″ M -MX]

[0097] Where Q is the error value;

[0098] If the error of the first channel is the smallest, then assign |Y1| = 0 to obtain a set of estimated initial error values. Similarly, by assigning any one of |Y2|...|Y4| to 0, we can obtain Z2,...,Z respectively. M Using Z1, Z2, ..., Z M Construct vectors D = [sum(Z1-Q), sum(Z2-Q), ..., sum(Z...] respectively. M [-Q)], sum() is the mean of the values ​​in parentheses. When there is one number less than 0 or two numbers meeting at 0 in D, and the variance of D is less than or equal to the threshold, the estimated initial error Z is obtained by selecting the channel containing the positive number closest to 0 in D as the reference channel. Otherwise, the estimated initial error Z is obtained by selecting the channel containing the negative number closest to 0 in D as the reference channel, denoted as . If there are N sampling times, then the average of the results obtained at the N sampling times will give the standard initial errors Y1, Y2, ..., Y... M .

[0099] Specifically, in this embodiment, see Figures 2-7This invention uses the collection of initial standard data and in-operation monitoring data of four sets of instrument transformers within the same substation as an example for illustration. This invention does not impose specific limitations; the number of instrument transformer sets is two or more and applies to this invention. The initial standard data refers to measurement data that has passed installation acceptance or calibration. Taking the collection of measurement data at 50 sampling points (i.e., 50 sampling times) as an example, the initial standard data of the four sets of three-phase capacitive voltage transformers, totaling 12 channels, is divided into a measurement unit according to phase. That is, the four sets of initial standard data for phase A, phase B, or phase C are divided into one measurement unit, resulting in three first measurement units. This invention uses the initial standard data for phase A as an example for illustration; the same applies to phase B or phase C. The first measurement unit is: X = {X1, X2, X3, X4}, where X... i ∈R 50*1 (i = 1, 2, 3, 4).

[0100] Specifically, in this embodiment, a first proportional value is obtained using initial standard data from four channels within the first metering unit. Any channel of any current transformer within the first metering unit is selected as a reference, and the first proportional value between different sets of in-phase initial standard data for the current transformer is calculated. The first proportional value has three parameters, and the first proportional value is:

[0101] kX 21 =mean(X2 / X1)

[0102] kX 31 =mean(X2 / X1)

[0103] kX 41 =mean(X4 / X1)

[0104] Here, mean() is the mean function, thus yielding three parameters kX from the raw measurement data within each measurement unit. 21 ,kX 31 ,kX 41 .

[0105] Specifically, in this embodiment, in-operation monitoring data of four sets of instrument transformers within the same substation are collected, totaling 12 channels of in-operation monitoring data. This in-operation monitoring data is divided by phase, with each phase grouped into a metering unit. The second metering unit is denoted as: X' = {X1', X2', X3', X4'}, where X... i '∈R N*1 (i = 1, 2, 3, 4), where N represents the number of sampling points.

[0106] Specifically, in this embodiment, a second proportional value is obtained using the on-operation monitoring data from four channels within the second metering unit. Taking any channel of any current transformer as a reference, the second proportional value of different groups of in-phase on-operation monitoring data from the current transformer is calculated. The second proportional value has four parameters, and the second proportional value is:

[0107] X″1=X′1

[0108] X″2=X′2 / kX 21

[0109] X″3=X′3 / kX 31

[0110] X″4=X′4 / kX 41

[0111] Specifically, by dividing the in-operation monitoring data by the first proportional value, the aim is to eliminate the differences between different groups of in-phase monitoring data caused by transformer and line parameter factors. The first proportional value is the error inherent in the instrument transformer itself. The error of the instrument transformer includes the initial error of the instrument transformer and its inherent error. By eliminating the influence of the inherent error of the in-operation monitoring data of the instrument transformer, the differences between different groups of in-phase monitoring data caused by transformer and line parameter factors are eliminated.

[0112] Specifically, in this embodiment, a system of equations is constructed using the initial error of each capacitive voltage transformer as the unknown, and the system of equations is solved to estimate the initial error of each capacitive voltage transformer in the same substation; any channel of any transformer is selected as a reference, and a monitoring model for each channel is constructed based on the second proportional value. The monitoring model is as follows:

[0113] X″1=(1+Y1)L

[0114] X″2=(1+Y2)L

[0115] X″3=(1+Y3)L

[0116] X″4=(1+Y4)L

[0117] Taking phase A as an example, Y1, Y2, Y3, and Y4 are the initial errors of the phase A channels of the first, second, third, and fourth groups of current transformers, respectively. L is the reference channel data, which represents the data of the first channel under error-free conditions. This data does not need to be obtained and is only used to explain that if each group of capacitive voltage transformers has no initial error, the in-phase data of different groups after processing in step S2 are equal.

[0118] Specifically, in this embodiment, the monitoring model is mathematically derived to obtain a set of equations, which are:

[0119] Y1-Y2=X″1 / X″2-1

[0120] Y2-Y3=X″2 / X″3-1

[0121] Y3-Y4=X″3 / X″4-1

[0122] Specifically, in this embodiment, to form a complete set of equations, a fourth equation needs to be constructed, which is independent of the set of equations. Within the second measurement unit, the channel with the smallest initial error among the four channels' in-operation monitoring data X″1, X″2, X″3, and X″4 is selected as the reference channel, and the reference channel is assigned zero, i.e.:

[0123] min(|Y1|,|Y2|,|Y3|,|Y4|)=0

[0124] Here, min() is the minimum value function.

[0125] Specifically, in this embodiment, the accuracy of the equation solution depends on the selection of the reference channel, including, for each sampling time, denoted as MX = mean(X″1,X″2,X″3,X″4), where MX represents the mean with respect to the second proportional value, mean() is the mean function, and an array Q is constructed, wherein the array Q is:

[0126] Q=[X″1-MX,X″2-MX,X″3-MX,X″4-MX]

[0127] Where Q is the error value;

[0128] If the error of the first channel is the smallest, then assign |Y1| = 0 to obtain a set of estimated initial error values. Similarly, by assigning |Y2|, |Y3|, or |Y4| to 0 respectively, we can obtain Z2, Z3, and Z4. Using Z1, Z2, Z3, and Z4, we construct vector D = [sum(Z1-Q), sum(Z2-Q), sum(Z3-Q), sum(Z4-Q)], where sum() is the mean of the values ​​in parentheses. When one number in D is less than 0 or two numbers meet at 0, and the variance of D is less than or equal to the threshold, the estimated initial error Z obtained when choosing the channel containing the positive number closest to 0 in D as the reference channel is used. Otherwise, the estimated initial error Z obtained when choosing the channel containing the negative number closest to 0 in D as the reference channel is used as the estimated initial error at this sampling time, denoted as Z. Finally, the results obtained from the 50 sampling times are averaged to obtain the standard initial errors Y1, Y2, Y3, and Y4.

[0129] Specifically, in this embodiment, initial standard data and in-operation monitoring data of M groups of instrument transformers in the same substation are collected to measure the initial error of the instrument transformers. The number of groups of instrument transformers is greater than or equal to 2, that is, M≥2. Other undisclosed methods are the same as collecting initial standard data and in-operation monitoring data of 4 groups of instrument transformers in the same substation to measure the initial error of the instrument transformers, and will not be elaborated upon in this invention.

[0130] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method of initial error metering of a power transformer, characterized by, The method comprises the following steps: S1, collecting initial standard data of M groups of mutual inductors in the same transformer substation, and calculating a first proportion value between initial standard data of different groups of mutual inductors in the same phase based on the initial standard data; S2, collecting in-service monitoring data of the M groups of mutual inductors in the same transformer substation, and calculating a second proportion value of in-service monitoring data of different groups of mutual inductors in the same phase based on the in-service monitoring data and the first proportion value; S3, constructing an equation group of initial errors of different groups of mutual inductors in the same phase according to the second proportion value, and solving the equation group to obtain initial errors of the M groups of mutual inductors in the same transformer substation, specifically as follows: S31, constructing a monitoring model of each channel according to the second proportion value; S32, mathematically deducing the monitoring model to obtain an equation group; S33, in the second metering unit, selecting a channel with the minimum initial error as a reference channel, and assigning zero to the initial error of the reference channel; S34, solving the equation group according to steps S32 and S33 to obtain the initial errors of the M groups of mutual inductors in the same transformer substation.

2. A method of initial error metering of a power transformer according to claim 1, characterized in that, After collecting the initial standard data of the M groups of mutual inductors in the same transformer substation in step S1, the method further comprises the following steps: The initial standard data is divided into one metering unit according to the phase, and the first metering unit is denoted as: ； wherein, is the first metering unit, is the in-phase data set in the initial standard data of the Mth mutual inductor, and M is the number of groups of mutual inductors.

3. A method of initial error metering of a power transformer according to claim 2, characterized in that, In step S1, the first proportion value between initial standard data of different groups of mutual inductors in the same phase is calculated, specifically as follows: Selecting any channel of any mutual inductor as a reference, the first proportion value between initial standard data of different groups of mutual inductors in the same phase is calculated, the first proportion value has M-1 parameters, and the first proportion value is: ； wherein, is a first ratio value for the 1st group and the Mth group of transformers, is a mean value calculation function.

4. A method of initial error metering of a power transformer according to claim 3, characterized in that, After collecting the in-service monitoring data of the M groups of mutual inductors in the same transformer substation in step S2, the method further comprises the following steps: The in-service monitoring data is divided into one metering unit according to the phase, and the second metering unit is denoted as: ； wherein, is a second metering unit, is a same-phase data set of the Mth mutual inductor in the operation monitoring data, and M is the number of groups of mutual inductors.

5. A method of initial error metering of a power transformer according to claim 4, characterized in that, In step S2, the second proportion value of in-service monitoring data of different groups of mutual inductors in the same phase is calculated based on the in-service monitoring data and the first proportion value, specifically as follows: Selecting any channel of any mutual inductor as a reference, the second proportion value of in-service monitoring data of different groups of mutual inductors in the same phase is calculated, the second proportion value has M parameters, and the second proportion value is: ； wherein, is the second proportional value for the Mth group of transformers.

6. A method of initial error metering of a power transformer according to claim 5, characterized in that, In step S31, the monitoring model of each channel is constructed according to the second proportion value, specifically as follows: Selecting any channel of any mutual inductor as a reference, the monitoring model of each channel is constructed according to the second proportion value, and the monitoring model is: ； wherein, is the initial error of any channel in the same metering unit of the Mth group of transformers, and L is the reference channel data.

7. A method of initial error metering of a power transformer according to claim 6, characterized in that, The equation group is: 。 8. A method of initial error metering of a power transformer according to claim 6, characterized in that, In step S33, in the second metering unit, a channel with the minimum initial error is selected as a reference channel, and the initial error of the reference channel is assigned to zero, specifically as follows: ； Wherein, min() is a minimum value function.

9. A method of initial error metering of a power transformer according to claim 1, characterized in that, The initial standard data is measurement data that is installed, accepted or qualified for testing.

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