Transformer on-line winding state evaluation method

Abstract

The embodiment of the invention discloses a transformer on-line winding state evaluation method. The method comprises the following steps: acquiring voltage signals at a high-voltage side bus and a neutral point; judging whether disturbance signals exist in the voltage signals or not; determining whether the disturbance signal is an effective disturbance signal; acquiring amplitudes of the amplitude-frequency response curve of the transformer under different frequencies; acquiring amplitudes of the amplitude-frequency response curve of the transformer under different frequencies when the line winding state is normal; carrying out subtraction on the two amplitudes to obtain a difference vector; segmenting and numbering the difference vector to obtain a quantile serial number vector; constructing a transfer matrix according to the quantile box number vector; determining a second moment, a positive offset coefficient, a negative offset coefficient and a stationary offset coefficient of the transfer matrix; determining a state evaluation factor; and evaluating the state of the transformer according to the state evaluation factor to obtain an evaluation result. According to the method, the online winding state of the transformer is evaluated, and the evaluation accuracy can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of transformer winding state assessment, and in particular to a transformer online winding state assessment method. Background Art

[0002] Transformers play a vital role in the generation, transmission, distribution and final use of electrical energy. Ensuring the stability and reliability of their performance is essential for the continued operation of the entire system. Numerous studies have pointed out that most transformer failures are caused by damage to their windings. These winding damages may be caused by mechanical loads during transportation and installation, or electrical stresses encountered during operation. Minor initial faults can put the transformer in an unfavorable working state, triggering a series of cumulative effects and accelerating its damage process. Therefore, timely diagnosis of the operating status of the transformer winding can effectively prevent the occurrence of unexpected transformer failures and ensure stable system operation.

[0003] For high-frequency signals, the winding of the transformer can be understood as a complex two-port network composed of components such as resistors, inductors and capacitors. When a winding fails, the parameters of these components, especially the values ​​of inductors and capacitors, will change accordingly. This change will further affect the transfer function of the two-port network model, causing the frequency response characteristics of the network to change. Therefore, in the prior art, the change in the frequency response characteristics of the winding is mainly analyzed to evaluate whether the winding is faulty. However, when the frequency response method is used to test and evaluate whether the winding is faulty, it is easily interfered by the adjacent electromagnetic field, resulting in inaccurate evaluation. Summary of the invention

[0004] Based on this, it is necessary to propose a transformer online winding status assessment method to address the above problems.

[0005] A method for evaluating an online winding state of a transformer, the method comprising:

[0006] Obtaining a voltage signal at a high-voltage side busbar and a voltage signal at a neutral point of the transformer;

[0007] Determine whether there is a disturbance signal in the voltage signal at the high-voltage side bus and the voltage signal at the neutral point;

[0008] In the case where a disturbance signal exists in the voltage signal at the high-voltage side bus and the voltage signal at the neutral point, determining whether the disturbance signal is a valid disturbance signal;

[0009] When it is determined that the disturbance signal is a valid disturbance signal, the voltage signal at the high-voltage side bus corresponding to the valid disturbance signal is used as the input signal, and the voltage signal at the neutral point is used as the output signal, and the amplitude of the transformer amplitude-frequency response curve at different frequencies is obtained;

[0010] Obtaining the amplitudes of the amplitude-frequency response curve at different frequencies when the transformer is in a normal online winding state;

[0011] Subtracting the amplitudes of the transformer amplitude-frequency response curve at different frequencies from the amplitudes of the transformer amplitude-frequency response curve at different frequencies when the transformer is in a normal online winding state to obtain a difference vector;

[0012] By segmenting and numbering the difference vector, a bin number vector is obtained;

[0013] Constructing a transfer matrix according to the bin number vector;

[0014] Determine the second-order moment of the transfer matrix, the positive offset coefficient, the negative offset coefficient and the stable offset coefficient according to each matrix value in the transfer matrix and the mean value of the transfer matrix;

[0015] Determine the state assessment factor through the second-order moment of the transfer matrix, the positive offset coefficient, the negative offset coefficient and the stable offset coefficient;

[0016] Evaluate the state of the transformer according to the state evaluation factor and obtain an evaluation result;

[0017] The step of obtaining a voltage signal at a high-voltage side busbar and a voltage signal at a neutral point of the transformer specifically includes:

[0018] Build a transformer online winding state assessment platform; the transformer online winding state assessment platform includes a grounding electrode, a neutral point voltage sensor, a neutral point bushing, a transformer high-voltage side A-phase bushing, a transformer high-voltage side B-phase bushing, a transformer high-voltage side C-phase bushing, a transformer high-voltage side A-phase voltage sensor, a transformer high-voltage side B-phase voltage sensor, a transformer high-voltage side C-phase voltage sensor, a transformer low-voltage side a-phase bushing, a transformer low-voltage side b-phase bushing, a transformer low-voltage side c-phase bushing, a transformer high-voltage side A-phase bus, a transformer high-voltage side B-phase bus, a transformer high-voltage side C-phase bus, a high-pass filter, a signal acquisition device, a data processing device, and a transformer; through the transformer online winding state assessment platform, obtain the voltage signal at the high-voltage side bus of the transformer and the voltage signal at the neutral point;

[0019] Wherein, when there is a disturbance signal in the voltage signal at the high-voltage side bus and the voltage signal at the neutral point, determining whether the disturbance signal is a valid disturbance signal specifically includes:

[0020] Calculate the peak time and half-peak time of the disturbance signal;

[0021] When the peak time of the disturbance signal is less than the first peak threshold and the half peak time is less than the second peak threshold, determining that the disturbance signal is a valid disturbance signal;

[0022] The bin number vector is specifically:

[0023]

[0024] D i =x i -y i (i=1,2,3...n)

[0025] Among them, M i is the i-th bin number vector, m is the number of bins, Q is the bin width, D i is the ith difference vector, max(D) is the maximum value of the difference vector, min(D) is the minimum value of the difference vector, x i is the amplitude of the transformer amplitude-frequency response curve at different frequencies, y i is the amplitude of the amplitude-frequency response curve at different frequencies when the transformer is in normal online winding state, and n is the number of frequency points of the amplitude-frequency response curve;

[0026] The transfer matrix is ​​specifically:

[0027]

[0028] Where W is the transfer matrix, w mm For each matrix value in the transfer matrix;

[0029] Among them, the second-order moment of the transfer matrix is ​​specifically:

[0030]

[0031] Among them, C1 is the second-order moment of the transfer matrix, w ij is the matrix value in the transfer matrix, indicating the M in the quantile bin number vector k =i and M k+1 = the number of combinations of j (k = 1, 2, 3…n-1), is the mean of the transfer matrix;

[0032] The positive offset coefficient is specifically:

[0033]

[0034] Where C2 is the positive offset coefficient;

[0035] The negative offset coefficient is specifically:

[0036]

[0037] Among them, C3 is the negative offset coefficient;

[0038] The stable deviation coefficient is specifically:

[0039]

[0040] Among them, C4 is the stable deviation coefficient, w ii is the matrix value in the transfer matrix, indicating the M in the quantile bin number vector k =i and M k+1 = the number of combinations of i (k = 1, 2, 3…n-1), w j，j+i is the matrix value in the transfer matrix, indicating the M in the quantile bin number vector k =j and M k+1 =j+i(k=1,2,3…n-1) number of combinations, w j，j-i is the matrix value in the transfer matrix, indicating the M in the quantile bin number vector k =j and M k+1 = the number of combinations of ji (k = 1, 2, 3 ... n-1);

[0041] Wherein, the state assessment factor includes a first state assessment factor, a second state assessment factor and a third state assessment factor;

[0042] The first status evaluation factor is specifically:

[0043]

[0044] Among them, η1 is the first state evaluation factor;

[0045] The second status evaluation factor is specifically:

[0046]

[0047] Wherein, η2 is the second state evaluation factor;

[0048] The third status evaluation factor is specifically:

[0049]

[0050] Among them, η3 is the third state evaluation factor;

[0051] The step of evaluating the state of the transformer according to the state evaluation factor and obtaining the evaluation result specifically includes:

[0052] When the first state assessment factor is less than the first assessment threshold, the second state assessment factor is less than the second assessment threshold, and the third state assessment factor is less than the second assessment threshold, it is assessed that the transformer is in good condition;

[0053] When the first state assessment factor is greater than or equal to the first assessment threshold and less than the third assessment threshold, the second state assessment factor is greater than or equal to the second assessment threshold and less than or equal to the first assessment threshold, and the third state assessment factor is less than the second assessment threshold, it is assessed that the transformer has a bulging warping fault;

[0054] When the first state assessment factor is greater than or equal to the first assessment threshold and less than the third assessment threshold, the second state assessment factor is less than the second assessment threshold, and the third state assessment factor is greater than or equal to the second assessment threshold and less than or equal to the first assessment threshold, it is assessed that the transformer has an axial displacement fault;

[0055] When the second state evaluation factor is greater than or equal to the first evaluation threshold, or the third state evaluation factor is greater than or equal to the first evaluation threshold, it is evaluated that an inter-panel short circuit fault occurs in the transformer.

[0056] The embodiments of the present invention have the following beneficial effects:

[0057] The present invention obtains the frequency response curve based on the disturbance signal to evaluate the online winding state of the transformer, which can accurately evaluate the transformer winding state, ensure the stable operation of the power system and the rapid maintenance of the transformer, which is very important for maintaining the continuity of the entire energy supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] 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, other drawings can be obtained based on these drawings without paying creative work.

[0059] in:

[0060] Figure 1 is a flow chart of a transformer online winding status assessment method in one embodiment;

[0061] Figure 2 Schematic diagram of a transformer online winding status assessment platform in one embodiment. DETAILED DESCRIPTION

[0062] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] The power system will inject a disturbance signal into the system when load is switched on and off, switches are operated, system protection devices are activated, lightning strikes, etc. When the rise and fall speeds of the disturbance signal are fast enough, it will contain a large number of high-frequency components. By collecting effective disturbance signals on the high-voltage side bus and the neutral point of the transformer, the frequency response curve of the transformer can be obtained. At present, there is no relevant standard for accurately judging the state of the transformer winding based on the frequency response curve obtained by the disturbance signal. To address this problem, combined with the advantage of convenient acquisition of disturbance signals, this embodiment proposes a transformer online winding state assessment method based on a disturbance signal rich in high-frequency components. It can effectively diagnose the state of the transformer winding, ensure the stable operation of the power system and the rapid maintenance of the transformer, which is crucial to maintaining the continuity of the entire energy supply.

[0064] Figure 1 FIG. 1 is a flow chart of a method for evaluating the status of an online transformer winding in one embodiment. Figure 1 As shown, the method specifically includes steps 101 to 111:

[0065] Step 101, obtaining a voltage signal at a high-voltage side busbar and a voltage signal at a neutral point of a transformer.

[0066] In this embodiment, by collecting effective disturbance signals on the high-voltage side busbar and the neutral point of the transformer, the frequency response curve of the transformer can be obtained.

[0067] The step 101 of obtaining the voltage signal at the high-voltage side busbar and the voltage signal at the neutral point of the transformer may further include steps 1011 to 1012:

[0068] Step 1011, building a transformer online winding status assessment platform.

[0069] Figure 2 FIG. 1 is a schematic diagram of a transformer online winding status assessment platform in one embodiment. Figure 2As shown, a transformer online winding state assessment platform comprises a grounding electrode (1), a transformer neutral point voltage sensor (2), a transformer neutral point bushing (3), a transformer high-voltage side A phase bushing (4a), a transformer high-voltage side B phase bushing (4b), a transformer high-voltage side C phase bushing (4c), a transformer high-voltage side A phase voltage sensor (5a), a transformer high-voltage side B phase voltage sensor (5b), a transformer high-voltage side C phase voltage sensor (5c), a transformer low-voltage side A phase bushing (6a), a transformer low-voltage side B phase bushing (6b), a transformer low-voltage side C phase bushing (6c), a transformer high-voltage side A phase bus (7a), a transformer high-voltage side B phase bus (7b), a transformer high-voltage side C phase bus (7c), a high-pass filter (8), a signal acquisition device (9), a data processing device (10), and a transformer (11); the system senses voltage signals at the high-voltage side bus and the neutral point through the voltage sensor, and inputs the signals into the signal processing device through the high-pass filter and the signal acquisition device.

[0070] Step 1012, obtaining a voltage signal at the high-voltage side bus and a voltage signal at the neutral point of the transformer through an online transformer winding status assessment platform.

[0071] In this embodiment, the voltage signals at the high-voltage bushing and the neutral point are obtained and recorded through the transformer online winding status assessment platform.

[0072] Step 102, determining whether there is a disturbance signal in the voltage signal at the high-voltage side bus and the voltage signal at the neutral point.

[0073] In this embodiment, the interference signal in the voltage signal is used to obtain the transformer amplitude-frequency response curve.

[0074] Step 103: When a disturbance signal exists in the voltage signal at the high-voltage side bus and the voltage signal at the neutral point, determine whether the disturbance signal is a valid disturbance signal.

[0075] In step 103, when there is a disturbance signal in the voltage signal at the high-voltage side bus and the voltage signal at the neutral point, determining whether the disturbance signal is a valid disturbance signal may further include steps 1031 to 1032:

[0076] Step 1031, calculating the peak time and half-peak time of the disturbance signal.

[0077] When a non-50Hz disturbance component appears in the voltage signal, calculate the peak time t of the disturbance signal at the high-voltage bushing. p and half peak time t s :

[0078] t p =t 100％ -t0％

[0079] t s =t 50％ -t 100％

[0080] Among them, t 0％ is the starting time of the disturbance signal, t 100％ is the moment when the disturbance signal amplitude reaches the maximum value, t 50％ It is the moment when the amplitude of the disturbance signal decays from the maximum value to half for the first time.

[0081] Step 1032: When the peak time of the disturbance signal is less than the first peak threshold and the half peak time is less than the second peak threshold, determine that the disturbance signal is a valid disturbance signal.

[0082] In this embodiment, when the peak time t of the disturbance signal at the high voltage bushing is p and half peak time t s When both are smaller than the corresponding set threshold, the disturbance signal is determined to be a valid disturbance signal.

[0083] The first peak threshold and the second peak threshold are set according to specific circumstances.

[0084] For example, according to the domestic standard document "GB / T 16927.1-2011" and the international standard document "IEC60071-1-2019": the standard transient operation overvoltage peak time is 250μs (±20%), and the half-peak time is 2500μs (±60%) of the impulse voltage. In order to ensure that the energy of the high-frequency component after FFT decomposition is high enough and the high-frequency part of the frequency response curve is not disturbed by noise, the rise time of the disturbance component must be fast enough. Through experiments, it can be found that the data is feasible when the rise time is 100us. In order to ensure the repeatability and reliability of the experiment, this article takes 50us as the threshold.

[0085] When t p <50us and t s When <2500us, the signal can be determined as a valid disturbance signal.

[0086] Step 104, when it is determined that the disturbance signal is a valid disturbance signal, the voltage signal at the high-voltage side bus corresponding to the valid disturbance signal is used as the input signal, and the voltage signal at the neutral point is used as the output signal, and the amplitude of the transformer amplitude-frequency response curve at different frequencies is obtained.

[0087] When the signal is determined to be a valid signal, the signal at the high-voltage bus is used as the input signal and the voltage signal at the neutral point is used as the output signal. Through computer processing, the amplitude-frequency response data at 1kHz-1MHz is obtained. The data at each frequency point are expressed as X=[(f1,x1), (f2,x2), (f3,x3)…(f n ,x n )].

[0088] Step 105 , obtaining the amplitudes at different frequencies of the amplitude-frequency response curve of the transformer when the online winding state is normal.

[0089] In this embodiment, the amplitudes of the transformer amplitude-frequency response curve at different frequencies obtained on-site are subtracted from the amplitudes of the amplitude-frequency response curve at different frequencies when the transformer winding is in a normal state to obtain a difference vector for subsequent calculation.

[0090] Step 106 , subtract the amplitudes of the transformer amplitude-frequency response curve at different frequencies from the amplitudes of the transformer amplitude-frequency response curve at different frequencies when the transformer is in a normal online winding state, to obtain a difference vector.

[0091] Step 107, obtaining a bin number vector by segmenting and numbering the difference vector.

[0092] The quantile box divides the value range of the difference vector, that is, the interval from the minimum value to the maximum value, into m equidistant continuous intervals to form m ranges.

[0093] The bin number is to divide the range of the maximum and minimum values ​​of the difference vector into 16 equally spaced intervals and mark them with integers. Q is the length of the segmented interval. The calculation process of M is: when the difference D is large, the point is assigned to the corresponding bin, and the bin number corresponding to the point is recorded. After calculating the multiple relationship between the difference vector and the bin interval length, rounding and adding one are performed. The role of the bin is to determine the number of the difference vector D.

[0094] The bin number vector is:

[0095]

[0096] D i =x i -y i (i=1,2,3...n)

[0097] Among them, M i is the i-th bin number vector, m is the number of bins (m=16), Q is the bin width, D i is the ith difference vector, max(D) is the maximum value of the difference vector, min(D) is the minimum value of the difference vector, xi is the amplitude of the transformer amplitude-frequency response curve at different frequencies, y i is the amplitude of the amplitude-frequency response curve at different frequencies when the transformer is in normal online winding state, and n is the number of frequency points of the amplitude-frequency response curve.

[0098] Step 108, constructing a transfer matrix according to the bin number vector.

[0099] The transfer matrix is:

[0100]

[0101] Where W is the transfer matrix, w mm For each matrix value in the transfer matrix.

[0102] Step 109, determining the second-order moment of the transfer matrix, the positive offset coefficient, the negative offset coefficient and the stable offset coefficient according to each matrix value in the transfer matrix and the mean value of the transfer matrix.

[0103] The second-order moment of the transfer matrix is:

[0104]

[0105] Among them, C1 is the second-order moment of the transfer matrix, w ij is the matrix value in the transfer matrix, indicating the M in the quantile bin number vector k =i and M k+1 = the number of combinations of j (k = 1, 2, 3…n-1), is the mean of the transfer matrix;

[0106] Positive offset coefficient, specifically:

[0107]

[0108] Where C2 is the positive offset coefficient;

[0109] Negative offset coefficient, specifically:

[0110]

[0111] Among them, C3 is the negative offset coefficient;

[0112] The stable deviation coefficient is:

[0113]

[0114] Among them, C4 is the stable deviation coefficient, w ii is the matrix value in the transfer matrix, indicating the M in the quantile bin number vector k =i and M k+1= the number of combinations of i (k = 1, 2, 3…n-1), w j，j+i is the matrix value in the transfer matrix, indicating the M in the quantile bin number vector k =j and M k+1 =j+i(k=1,2,3…n-1) number of combinations, w j，j-i is the matrix value in the transfer matrix, indicating the M in the quantile bin number vector k =j and M k+1 =The number of combinations of ji(k=1,2,3…n-1).

[0115] Step 110, determining the state assessment factor through the second-order moment of the transfer matrix, the positive offset coefficient, the negative offset coefficient and the stable offset coefficient.

[0116] In this embodiment, the state evaluation factors η1, η2, and η3 are calculated by the second-order moment C1 of the transfer matrix, the positive offset coefficient C2, the negative offset coefficient C3, and the stable offset coefficient C4.

[0117] In some examples, the state assessment factors include a first state assessment factor, a second state assessment factor, and a third state assessment factor.

[0118] The first status evaluation factor is:

[0119]

[0120] Among them, η1 is the first state evaluation factor;

[0121] The second status evaluation factor is:

[0122]

[0123] Wherein, η2 is the second state evaluation factor;

[0124] The third status assessment factor is:

[0125]

[0126] Wherein, η3 is the third state evaluation factor.

[0127] Step 111, evaluating the state of the transformer according to the state evaluation factor, and obtaining an evaluation result.

[0128] In step 111, the state of the transformer is evaluated according to the state evaluation factor to obtain the evaluation result, which may further include steps 1111 to 1114:

[0129] Step 1111: When the first state assessment factor is less than the first assessment threshold, the second state assessment factor is less than the second assessment threshold, and the third state assessment factor is less than the second assessment threshold, it is assessed that the transformer is in good state.

[0130] Step 1112, when the first state evaluation factor is greater than or equal to the first evaluation threshold and less than the third evaluation threshold, the second state evaluation factor is greater than or equal to the second evaluation threshold and less than or equal to the first evaluation threshold, and the third state evaluation factor is less than the second evaluation threshold, it is evaluated that the transformer has a bulging warping fault.

[0131] Step 1113, when the first state assessment factor is greater than or equal to the first assessment threshold and less than the third assessment threshold, the second state assessment factor is less than the second assessment threshold, and the third state assessment factor is greater than or equal to the second assessment threshold and less than or equal to the first assessment threshold, it is assessed that the transformer has an axial displacement fault.

[0132] Step 1114: When the second state evaluation factor is greater than or equal to the first evaluation threshold, or when the third state evaluation factor is greater than or equal to the first evaluation threshold, it is evaluated that an inter-panel short circuit fault occurs in the transformer.

[0133] The first evaluation threshold, the second evaluation threshold, and the third evaluation threshold are determined according to specific circumstances and are not limited here.

[0134] Exemplarily, the first evaluation threshold is set to 1.2, the second evaluation threshold is set to 1.0, and the third evaluation threshold is set to 1.4.

[0135] When η1<1.2, η2<1.0 and η3<1.0, the transformer winding is in good condition and has no faults;

[0136] When 1.4>η1≥1.2, 1.2≥η2≥1.0, η3<1.0, the transformer will have bulging and warping fault;

[0137] When 1.4>η1≥1.2, 1.2≥η3≥1.0, η2<1.0, the transformer has an axial displacement fault;

[0138] When η2≥1.2 or η3≥1.2, a short circuit fault occurs between the transformer and the wafer.

[0139] The present invention obtains the frequency response curve based on the disturbance signal to evaluate the online winding state of the transformer, which can accurately evaluate the transformer winding state, ensure the stable operation of the power system and the rapid maintenance of the transformer, which is very important for maintaining the continuity of the entire energy supply.

[0140] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0141] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0142] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for evaluating the status of an online transformer winding, characterized in that: The method comprises: Obtaining a voltage signal at a high-voltage side busbar and a voltage signal at a neutral point of the transformer; Determine whether there is a disturbance signal in the voltage signal at the high-voltage side bus and the voltage signal at the neutral point; In the case where a disturbance signal exists in the voltage signal at the high-voltage side bus and the voltage signal at the neutral point, determining whether the disturbance signal is a valid disturbance signal; When it is determined that the disturbance signal is a valid disturbance signal, the voltage signal at the high-voltage side bus corresponding to the valid disturbance signal is used as the input signal, and the voltage signal at the neutral point is used as the output signal, and the amplitude of the transformer amplitude-frequency response curve at different frequencies is obtained; Obtaining the amplitudes of the amplitude-frequency response curve at different frequencies when the transformer is in a normal online winding state; Subtracting the amplitudes of the transformer amplitude-frequency response curve at different frequencies from the amplitudes of the transformer amplitude-frequency response curve at different frequencies when the transformer is in a normal online winding state to obtain a difference vector; By segmenting and numbering the difference vector, a bin number vector is obtained; Constructing a transfer matrix according to the bin number vector; Determine the second-order moment of the transfer matrix, the positive offset coefficient, the negative offset coefficient and the stable offset coefficient according to each matrix value in the transfer matrix and the mean value of the transfer matrix; Determine the state assessment factor through the second-order moment of the transfer matrix, the positive offset coefficient, the negative offset coefficient and the stable offset coefficient; Evaluate the state of the transformer according to the state evaluation factor and obtain an evaluation result; The step of obtaining a voltage signal at a high-voltage side busbar and a voltage signal at a neutral point of the transformer specifically includes: Build a transformer online winding state assessment platform; the transformer online winding state assessment platform includes a grounding electrode, a neutral point voltage sensor, a neutral point bushing, a transformer high-voltage side A-phase bushing, a transformer high-voltage side B-phase bushing, a transformer high-voltage side C-phase bushing, a transformer high-voltage side A-phase voltage sensor, a transformer high-voltage side B-phase voltage sensor, a transformer high-voltage side C-phase voltage sensor, a transformer low-voltage side a-phase bushing, a transformer low-voltage side b-phase bushing, a transformer low-voltage side c-phase bushing, a transformer high-voltage side A-phase bus, a transformer high-voltage side B-phase bus, a transformer high-voltage side C-phase bus, a high-pass filter, a signal acquisition device, a data processing device, and a transformer; The voltage signal at the high-voltage side busbar and the voltage signal at the neutral point of the transformer are obtained through the transformer online winding status assessment platform; Wherein, when there is a disturbance signal in the voltage signal at the high-voltage side bus and the voltage signal at the neutral point, determining whether the disturbance signal is a valid disturbance signal specifically includes: Calculate the peak time and half-peak time of the disturbance signal; When the peak time of the disturbance signal is less than the first peak threshold and the half peak time is less than the second peak threshold, determining that the disturbance signal is a valid disturbance signal; The bin number vector is specifically: D i =x i -y i (i=1,2,3...n) Among them, M i is the i-th bin number vector, m is the number of bins, Q is the bin width, D i is the ith difference vector, max(D) is the maximum value of the difference vector, min(D) is the minimum value of the difference vector, x i is the amplitude of the transformer amplitude-frequency response curve at different frequencies, y i is the amplitude of the amplitude-frequency response curve at different frequencies when the transformer is in normal online winding state, and n is the number of frequency points of the amplitude-frequency response curve; The transfer matrix is ​​specifically: Where W is the transfer matrix, w mm For each matrix value in the transfer matrix; Among them, the second-order moment of the transfer matrix is ​​specifically: Among them, C1 is the second-order moment of the transfer matrix, w ij is the matrix value in the transfer matrix, indicating the M in the quantile bin number vector k =i and M k+1 = the number of combinations of j (k = 1, 2, 3…n-1), is the mean of the transfer matrix; The positive offset coefficient is specifically: Where C2 is the positive offset coefficient; The negative offset coefficient is specifically: Among them, C3 is the negative offset coefficient; The stable deviation coefficient is specifically: Among them, C4 is the stable deviation coefficient, w ii is the matrix value in the transfer matrix, indicating the M in the quantile bin number vector k =i and M k+1 = the number of combinations of i (k = 1, 2, 3…n-1), w j，j+i is the matrix value in the transfer matrix, indicating the M in the quantile bin number vector k =j and M k+1 =j+i(k=1,2,3…n-1) number of combinations, w j，j-i is the matrix value in the transfer matrix, indicating the M in the quantile bin number vector k =j and M k+1 = the number of combinations of ji (k = 1, 2, 3 ... n-1); Wherein, the state assessment factor includes a first state assessment factor, a second state assessment factor and a third state assessment factor; The first status evaluation factor is specifically: Among them, η1 is the first state evaluation factor; The second status evaluation factor is specifically: Wherein, η2 is the second state evaluation factor; The third status evaluation factor is specifically: Among them, η3 is the third state evaluation factor; The step of evaluating the state of the transformer according to the state evaluation factor and obtaining the evaluation result specifically includes: When the first state assessment factor is less than the first assessment threshold, the second state assessment factor is less than the second assessment threshold, and the third state assessment factor is less than the second assessment threshold, it is assessed that the transformer is in good condition; When the first state assessment factor is greater than or equal to the first assessment threshold and less than the third assessment threshold, the second state assessment factor is greater than or equal to the second assessment threshold and less than or equal to the first assessment threshold, and the third state assessment factor is less than the second assessment threshold, it is assessed that the transformer has a bulging warping fault; When the first state assessment factor is greater than or equal to the first assessment threshold and less than the third assessment threshold, the second state assessment factor is less than the second assessment threshold, and the third state assessment factor is greater than or equal to the second assessment threshold and less than or equal to the first assessment threshold, it is assessed that the transformer has an axial displacement fault; When the second state evaluation factor is greater than or equal to the first evaluation threshold, or the third state evaluation factor is greater than or equal to the first evaluation threshold, it is evaluated that an inter-panel short circuit fault occurs in the transformer.

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