A method and device for monitoring transient mechanical state of transformer winding

Abstract

The embodiment of the present invention discloses a method and device for monitoring the transient mechanical state of a transformer winding, wherein the method comprises: calculating the difference between the bidirectional transfer entropy between the sub-band signal energy sequence output by the J-layer filter group of the spectrum distribution of the current transient vibration signal and the historical sub-band signal energy sequence to construct a main factor band signal energy sequence, and then calculating the transfer entropy change rate based on the sub-band signal energy sequence and the main factor band signal energy sequence, so as to realize the use of the transfer entropy change rate to distinguish the transient mechanical state of the transformer winding. By obtaining the transfer entropy change rate through the difference between the bidirectional transfer entropy between the sub-band signal energy sequence and the historical sub-band signal energy sequence, the transient mechanical state of the transformer winding before and after can be compared efficiently and accurately, thereby effectively distinguishing the transient mechanical state of the transformer winding under a short-circuit impact.

Description

Technical Field

[0001] The present invention relates to the technical field of signal monitoring, and in particular to a method and device for monitoring the transient mechanical state of a transformer winding. Background Art

[0002] With the rapid development of my country's economy, the speed of power grid construction has been significantly accelerated. The rapid increase in system capacity and the increase in the capacity of a single large main transformer have also increased the short-circuit electric force acting on the transformer winding. When a short-circuit fault occurs, the transformer winding will become loose or slightly deformed. In severe cases, the insulation and structural parts of the transformer winding may be damaged, thereby affecting the insulation performance of the transformer winding, and even causing the winding to twist, deform, loosen, and break the wire. In practical applications, if the looseness or deformation of the transformer winding cannot be discovered and repaired in time, then when the looseness and deformation of the transformer winding accumulate to a certain extent, its mechanical stability will be greatly affected and its short-circuit resistance will be greatly reduced. Even if it is subjected to a small impact current, it will cause a major accident. In addition, the aging of the oil-paper insulation of the operating transformer will also cause the winding to become gradually loose and unstable, resulting in a decrease in the transformer's short-circuit resistance and potential accident hazards. Therefore, how to accurately monitor the mechanical state of the transformer winding after a short-circuit impact and prevent the risk of transformer winding deformation caused by the cumulative effect is of great practical significance for improving the reliability of transformer operation. Summary of the invention

[0003] The main purpose of the present invention is to provide a method and device for monitoring the transient mechanical state of a transformer winding, which can solve the problem of low effectiveness of mechanical state monitoring in the prior art.

[0004] To achieve the above object, the present invention provides a method for monitoring the transient mechanical state of a transformer winding in a first aspect, the method comprising:

[0005] Collecting a current transient vibration signal when the transformer is subjected to a short-circuit impact, normalizing the current transient vibration signal, and performing a discrete Fourier transform on the normalized current transient vibration signal to obtain a frequency spectrum distribution of the normalized current transient vibration signal;

[0006] Design a J-layer filter bank according to the frequency spectrum distribution, and calculate a sub-band signal energy sequence output by the J-layer filter bank of the frequency spectrum distribution;

[0007] Calculating the difference in bidirectional transfer entropy between the sub-band signal energy sequence and the historical sub-band signal energy sequence, and constructing a main factor band signal energy sequence according to the difference in bidirectional transfer entropy; wherein the historical sub-band signal energy sequence is a sub-band signal energy sequence obtained according to a historical transient vibration signal obtained before the current transient vibration signal;

[0008] The transfer entropy change rate is calculated according to the sub-band signal energy sequence and the main factor frequency band signal energy sequence, and the transient mechanical state of the transformer winding is judged according to the transfer entropy change rate.

[0009] In combination with the first aspect, in a possible implementation manner, the step of designing a J-layer filter bank according to the spectrum distribution includes:

[0010] The quality factor and the scale transformation coefficient are calculated according to the spectrum distribution, and the calculation formula is:

[0011] Q=f / BW

[0012]

[0013]

[0014] Wherein, Q represents the quality factor; f refers to 100 Hz in the spectrum distribution; BW refers to the 3 dB bandwidth corresponding to the amplitude of the 100 Hz component; α and β represent the scaling coefficients;

[0015] The number of decomposition layers of the filter bank is calculated according to the quality factor and the scale transformation coefficient, and the calculation formula is:

[0016]

[0017] Where J represents the number of decomposition layers of the filter bank; N is the length of the spectrum distribution; round(·) is the rounding function;

[0018] A J-layer filter bank is formed by using low-pass filters and high-pass filters, wherein according to the j-th layer high-pass filter H 0,j (k) and the j-th low-pass filter H 1,j (k), forming the j-th layer filter; where j ranges from 1 to J.

[0019] In combination with the first aspect, in a possible implementation method, the above-mentioned calculation of the sub-band signal energy sequence output by the J-layer filter group of the spectrum distribution includes: letting the spectrum distribution be the initial input V0(0) of the J-layer filter group, and sequentially calculating the sub-band signals output by the J-layer filter group; and calculating the sub-band signal energy sequence according to the sub-band signal V1(j) output by the j-th layer low-pass filter.

[0020] In combination with the first aspect, in a possible implementation manner, the calculation formulas for the sub-band signal V1(j) output by the j-th layer low-pass filter are respectively:

[0021] V1(j)=V1(j-1)·H 1，j

[0022] Among them, H 1，j Represents the j-th low-pass filter; the value of j is 1 to J.

[0023] In combination with the first aspect, in a possible implementation manner, the calculating the difference between the bidirectional transfer entropy of the sub-band signal energy sequence and the historical sub-band signal energy sequence includes:

[0024] The bidirectional transfer entropies corresponding to the J elements in the sub-band signal energy sequence E and the historical sub-band signal energy sequence E' are calculated in sequence, wherein the calculation formula for the bidirectional transfer entropy of the j-th element is:

[0025]

[0026]

[0027] Where T represents the bidirectional transfer entropy; h represents the entropy rate; p represents the probability; and are s-order and r-order Markov processes respectively, and E' j,t+1 ={E' j,t-s+1 ,…,E' j,t}and The value of j ranges from 1 to J;

[0028] The difference of the bidirectional transfer entropy is calculated.

[0029] In combination with the first aspect, in a possible implementation manner, the step of calculating the transfer entropy change rate according to the sub-band signal energy sequence and the main factor band signal energy sequence includes:

[0030] The calculation formula for calculating the transfer entropy change rate η according to the sub-band signal energy sequence and the main factor band signal energy sequence is:

[0031]

[0032] Where T represents the bidirectional transfer entropy, E j represents the jth element in the sub-band signal energy sequence, E j ' represents the jth element in the historical sub-band signal energy sequence, and w represents the number of main sub-band signal energy sequences.

[0033] In combination with the first aspect, in a possible implementation, the j-th layer high-pass filter H 0,j (k) and the j-th low-pass filter H 1,j The calculation formula of (k) is:

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040] Wherein, θ(k) and θ(Nk) are the transition frequency band functions of the filter; round(·) is the rounding function; P(j) is the passband of the j-th filter, S(j) is the cutoff frequency band of the j-th filter, and T(j) is the transition frequency band of the j-th filter; α and β represent the scaling coefficients; N is the length of the spectrum distribution; and j ranges from 1 to J.

[0041] In combination with the first aspect, in a possible implementation method, the above-mentioned judging the transient mechanical state of the transformer winding based on the transfer entropy change rate includes: when the transfer entropy change rate is greater than a preset threshold, it is judged that the transient mechanical state of the transformer winding has changed; when the transfer entropy change rate is less than or equal to the preset threshold, it is judged that the transient mechanical state of the transformer winding has not changed.

[0042] To achieve the above object, the second aspect of the present invention provides a transformer winding transient mechanical state monitoring device, the device comprising:

[0043] An acquisition module is used to collect a current transient vibration signal when the transformer is subjected to a short-circuit shock, normalize the current transient vibration signal, and perform a discrete Fourier transform on the normalized current transient vibration signal to obtain a frequency spectrum distribution of the normalized current transient vibration signal;

[0044] A calculation module is used to design a J-layer filter group according to the frequency spectrum distribution, and calculate the sub-band signal energy sequence output by the J-layer filter group of the frequency spectrum distribution;

[0045] A construction module: used to calculate the difference between the bidirectional transfer entropy of the sub-band signal energy sequence and the historical sub-band signal energy sequence, and construct the main factor frequency band signal energy sequence according to the difference between the bidirectional transfer entropy;

[0046] A discrimination module is used to calculate the transfer entropy change rate according to the sub-band signal energy sequence and the main factor frequency band signal energy sequence, and to discriminate the transient mechanical state of the transformer winding according to the transfer entropy change rate.

[0047] In conjunction with the second aspect, in a possible implementation manner, the identification module includes:

[0048] State judgment module: when the transfer entropy change rate is greater than a preset threshold, it is judged that the transient mechanical state of the transformer winding has changed; when the transfer entropy change rate is less than or equal to the preset threshold, it is judged that the transient mechanical state of the transformer winding has not changed.

[0049] To achieve the above object, the third aspect of the present invention provides a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor performs the following steps:

[0050] Collecting a current transient vibration signal when the transformer is subjected to a short-circuit impact, normalizing the current transient vibration signal, and performing a discrete Fourier transform on the normalized current transient vibration signal to obtain a frequency spectrum distribution of the normalized current transient vibration signal;

[0051] Design a J-layer filter bank according to the frequency spectrum distribution, and calculate a sub-band signal energy sequence output by the J-layer filter bank of the frequency spectrum distribution;

[0052] Calculating the difference in bidirectional transfer entropy between the sub-band signal energy sequence and the historical sub-band signal energy sequence, and constructing a main factor band signal energy sequence according to the difference in bidirectional transfer entropy; wherein the historical sub-band signal energy sequence is a sub-band signal energy sequence obtained according to a historical transient vibration signal obtained before the current transient vibration signal;

[0053] The transfer entropy change rate is calculated according to the sub-band signal energy sequence and the main factor frequency band signal energy sequence, and the transient mechanical state of the transformer winding is judged according to the transfer entropy change rate.

[0054] To achieve the above object, a fourth aspect of the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the following steps:

[0055] Collecting a current transient vibration signal when the transformer is subjected to a short-circuit impact, normalizing the current transient vibration signal, and performing a discrete Fourier transform on the normalized current transient vibration signal to obtain a frequency spectrum distribution of the normalized current transient vibration signal;

[0056] Design a J-layer filter bank according to the frequency spectrum distribution, and calculate a sub-band signal energy sequence output by the J-layer filter bank of the frequency spectrum distribution;

[0057] Calculating the difference in bidirectional transfer entropy between the sub-band signal energy sequence and the historical sub-band signal energy sequence, and constructing a main factor band signal energy sequence according to the difference in bidirectional transfer entropy; wherein the historical sub-band signal energy sequence is a sub-band signal energy sequence obtained according to a historical transient vibration signal obtained before the current transient vibration signal;

[0058] The transfer entropy change rate is calculated according to the sub-band signal energy sequence and the main factor frequency band signal energy sequence, and the transient mechanical state of the transformer winding is judged according to the transfer entropy change rate.

[0059] The embodiments of the present invention have the following beneficial effects:

[0060] The present invention provides a transformer winding transient mechanical state monitoring method, which calculates the difference between the bidirectional transfer entropy between the sub-band signal energy sequence output by the J-layer filter group of the spectrum distribution of the current transient vibration signal and the historical sub-band signal energy sequence obtained according to the historical transient vibration signal, constructs the main factor frequency band signal energy sequence according to the difference in the bidirectional transfer entropy, and then calculates the transfer entropy change rate according to the sub-band signal energy sequence and the main factor frequency band signal energy sequence, and discriminates the transformer winding transient mechanical state according to the transfer entropy change rate. The transfer entropy change rate is obtained by the difference in the bidirectional transfer entropy between the sub-band signal energy sequence and the historical sub-band signal energy sequence, and the transient mechanical state of the transformer winding before and after can be compared efficiently and accurately, thereby effectively discriminating the transformer winding transient mechanical state under short-circuit impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] 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.

[0062] in:

[0063] Figure 1 It is a schematic flow chart of a method for monitoring transient mechanical state of transformer windings in an embodiment of the present invention;

[0064] Figure 2 It is a structural block diagram of a transformer winding transient mechanical state monitoring device in an embodiment of the present invention;

[0065] Figure 3 4 is a structural block diagram of a computer device in an embodiment of the present invention. DETAILED DESCRIPTION

[0066] 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.

[0067] The operating transformer will continuously generate core vibration and winding vibration. The core vibration is mainly caused by the hysteresis expansion force of the silicon steel sheet, which is related to the working voltage of the transformer, while the winding vibration is mainly caused by the electromotive force generated by the interaction between the load and the transformer magnetic field, which is closely related to the load current. When there is an outlet short circuit in the power grid, the short-circuit electromotive force acting on the transformer winding surges, the winding vibration intensifies, and a transient vibration signal is formed. These transient vibration signals are transmitted to the surface of the box wall through insulating oil and transformer mechanical structural parts, becoming the main contributor to the transformer box wall vibration signal. The transformer winding is mainly a mechanical structure formed by winding electromagnetic wire according to a certain structure. Any changes in its mechanical structure can be reflected from the changes in its mechanical characteristics, and the vibration signal can well reflect the mechanical characteristics. Therefore, the vibration signal can be processed to identify any changes in the mechanical structure.

[0068] The embodiment of the present invention provides a method for monitoring the transient mechanical state of a transformer winding. Figure 1 , Figure 1 A schematic diagram of a flow chart of a method for monitoring the transient mechanical state of a transformer winding provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the specific steps of this method are as follows:

[0069] Step S101, collecting a current transient vibration signal when the transformer is subjected to a short-circuit shock, normalizing the current transient vibration signal, and performing a discrete Fourier transform on the normalized current transient vibration signal to obtain a frequency spectrum distribution of the normalized current transient vibration signal.

[0070] The transient vibration signal v(k) is collected when the transformer is subjected to a short-circuit shock. The transient vibration signal is the transient vibration signal at the current collection moment. In this embodiment, it is referred to as the current transient vibration signal. The current transient vibration signal is obtained by a vibration acceleration sensor placed on the wall of the transformer oil tank. The sampling frequency of the current transient vibration signal is f0 and the length is N0.

[0071] In order to improve the effectiveness of obtaining the current transient vibration signal, the current transient vibration signal v(k) is normalized, wherein the normalization calculation formula for the current transient vibration signal v(k) is:

[0072]

[0073] Where: v'(k) is the normalized current transient vibration signal, and N0 is the length of the current transient vibration signal.

[0074] Perform N-point discrete Fourier transform on the normalized current transient vibration signal v(t) to obtain the spectrum distribution Y(f) of the normalized current transient vibration signal v(t), wherein the calculation formula of the spectrum distribution of the normalized current transient vibration signal is:

[0075]

[0076] Wherein, v'(k) is the normalized current transient vibration signal, and N is the length of the spectrum distribution Y(f).

[0077] Step S102: designing a J-layer filter bank according to the frequency spectrum distribution, and calculating a sub-band signal energy sequence output by the J-layer filter bank of the frequency spectrum distribution.

[0078] The quality factor Q, the scale transformation coefficients α and β, and the number of decomposition layers J of the filter bank are calculated according to the normalized spectrum distribution of the current transient vibration signal. The calculation formulas are:

[0079] Q=f / BW

[0080]

[0081]

[0082]

[0083] Where: f refers to 100 Hz in the spectrum distribution Y(f); BW refers to the 3 dB bandwidth corresponding to the amplitude of the 100 Hz component; round(·) is the rounding function.

[0084] The design uses low-pass filter H1 and high-pass filter H0 to form a J-layer filter bank, where according to the j-th layer high-pass filter H 0,j (k) and the j-th low-pass filter H 1,j (k), forming the j-th layer filter, the j-th layer high-pass filter H 0,j (k) and the j-th low-pass filter H 1,j The calculation formulas for (k) are:

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091] Where: θ is the transition frequency band function of the filter, that is, θ(k) and θ(Nk) are the transition frequency band functions of the filter; round(·) is the rounding function; P(j) is the passband of the j-th filter, S(j) is the cutoff frequency band of the j-th filter, and T(j) is the transition frequency band of the j-th filter; α and β represent the scale transformation coefficients; N is the length of the spectrum distribution.

[0092] Let the spectrum distribution Y(f) be the initial input V0(0) of the designed J-layer filter group, and calculate the sub-band signals output by the designed J-layer filter group in sequence. It can be understood as letting the spectrum distribution Y(f) be the initial input V0(0) of the j-th high-pass filter and the j-th low-pass filter in the designed J-layer filter group, and finally outputting the sub-band signals of the j-th high-pass filter and the j-th low-pass filter in sequence, where the value of j ranges from 1 to J.

[0093] Among them, the calculation formulas of the sub-band signal V0(j) output by the j-th layer high-pass filter and the sub-band signal V1(j) output by the j-th layer low-pass filter are respectively:

[0094] V0(j)=V0(j-1)·H 0,j j=1,2,…,J

[0095] V1(j)=V1(j-1)·H 1,j j=1,2,…,J

[0096] Among them, H 0，j represents the j-th layer high-pass filter; H 1，j represents the j-th low-pass filter.

[0097] According to the sub-band signal V1(j) output by the j-th layer low-pass filter, the value of j ranges from 1 to J, that is, according to the sub-band signals output by all low-pass filters, the sub-band signal energy sequence E = [E1, E2, ..., E J ], specifically, the sub-band signal energy sequence is composed of the sub-band signals V1(j) output by the J-layer low-pass filter group, j=1,2,…,J, wherein the calculation formula of the sub-band signal energy sequence is:

[0098]

[0099] Among them, E j Represents the jth element in the sub-band signal energy sequence; V1(j) (t) represents the sub-band signal output by the j-th layer low-pass filter bank.

[0100] Step S103: Calculate the difference in bidirectional transfer entropy between the sub-band signal energy sequence and the historical sub-band signal energy sequence, and construct a main factor frequency band signal energy sequence according to the difference in bidirectional transfer entropy.

[0101] The historical sub-frequency band signal energy sequence is a sub-frequency band signal energy sequence obtained based on the historical transient vibration signal obtained before the current transient vibration signal.

[0102] In this embodiment, the transient vibration signal of the transformer is collected in real time, and a method for calculating the sub-band signal energy sequence is adopted. According to the transient vibration signal of the transformer collected in real time, the corresponding sub-band signal energy sequence is calculated in real time, and the calculated sub-band signal energy sequence is stored as a historical sub-band signal energy sequence.

[0103] In this embodiment, after the sub-band signal energy sequence is obtained in step 102, the difference in bidirectional transfer entropy between the sub-band signal energy sequence and the historical sub-band signal energy sequence is further calculated.

[0104] The difference of the bidirectional transfer entropy is calculated specifically by sequentially calculating the bidirectional transfer entropies corresponding to J elements in the sub-band signal energy sequence E and the historical sub-band signal energy sequence E', wherein the calculation formula of the bidirectional transfer entropy of the j-th element is:

[0105]

[0106]

[0107] Where T represents the bidirectional transfer entropy; h represents the entropy rate; p represents the probability; and are s-order and r-order Markov processes respectively, and E' j,t+1 ={E' j,t-s+1 ,…,E' j,t}and Finally, the difference between the bidirectional transfer entropies is calculated.

[0108] Furthermore, the main factor frequency band signal energy sequence is constructed according to the difference of the two-way transfer entropy, and the condition it satisfies is T(E' j →E j )>0 and T(E j →E' j )<0.

[0109] Step S104: Calculate the transfer entropy change rate according to the sub-band signal energy sequence and the main factor frequency band signal energy sequence, and judge the transient mechanical state of the transformer winding according to the transfer entropy change rate.

[0110] The transfer entropy change rate η is calculated according to the sub-band signal energy sequence and the main factor band signal energy sequence, and its calculation formula is:

[0111]

[0112] Where T represents the bidirectional transfer entropy, E j represents the jth element in the sub-band signal energy sequence, E j ' represents the jth element in the historical sub-band signal energy sequence, and w represents the number of main sub-band signal energies.

[0113] The transient mechanical state of the transformer winding is judged according to the transfer entropy change rate. Specifically, when the transfer entropy change rate is greater than a preset threshold, it is judged that the transient mechanical state of the transformer winding has changed, and timely maintenance is required to avoid major failures. When the transfer entropy change rate is less than or equal to the preset threshold, it is judged that the transient mechanical state of the transformer winding has not changed. The preset threshold can be set according to experience, such as 30%.

[0114] Based on the above method, by calculating the difference between the bidirectional transfer entropy between the sub-band signal energy sequence output by the J-layer filter group of the spectrum distribution of the current transient vibration signal and the historical sub-band signal energy sequence obtained according to the historical transient vibration signal, the main factor band signal energy sequence is constructed according to the difference in bidirectional transfer entropy, and then the transfer entropy change rate is calculated according to the sub-band signal energy sequence and the main factor band signal energy sequence, and the transient mechanical state of the transformer winding is judged according to the transfer entropy change rate. The transfer entropy change rate is obtained by the difference in bidirectional transfer entropy between the sub-band signal energy sequence and the historical sub-band signal energy sequence, which can efficiently and accurately compare the transient mechanical states of the transformer winding before and after, thereby effectively judging the transient mechanical state of the transformer winding under short-circuit impact.

[0115] In order to better implement the above method, the embodiment of the present invention provides a transformer winding transient mechanical state monitoring device, referring to Figure 2 , Figure 2 A structural block diagram of a transformer winding transient mechanical state monitoring device provided by an embodiment of the present invention, such as Figure 2 As shown, the device 20 comprises:

[0116] Acquisition module 201: used to collect the current transient vibration signal when the transformer is subjected to short-circuit impact, normalize the current transient vibration signal, and perform discrete Fourier transform on the normalized current transient vibration signal to obtain the frequency spectrum distribution of the normalized current transient vibration signal.

[0117] The calculation module 202 is used to design a J-layer filter bank according to the frequency spectrum distribution, and calculate the sub-band signal energy sequence output by the J-layer filter bank of the frequency spectrum distribution.

[0118] Construction module 203: used to calculate the difference of the bidirectional transfer entropy between the sub-frequency band signal energy sequence and the historical sub-frequency band signal energy sequence, and construct the main factor frequency band signal energy sequence according to the difference of the bidirectional transfer entropy.

[0119] The determination module 204 is configured to calculate the transfer entropy change rate according to the sub-band signal energy sequence and the main factor frequency band signal energy sequence, and determine the transient mechanical state of the transformer winding according to the transfer entropy change rate.

[0120] In a possible design, the calculation module 202 is specifically used to design a J-layer filter bank according to the spectrum distribution, including:

[0121] The quality factor and the scale transformation coefficient are calculated according to the spectrum distribution, and the calculation formula is:

[0122] Q=f / BW

[0123]

[0124]

[0125] Wherein, Q represents the quality factor; f refers to 100 Hz in the spectrum distribution; BW refers to the 3 dB bandwidth corresponding to the amplitude of the 100 Hz component; α and β represent the scaling coefficients;

[0126] The number of decomposition layers of the filter bank is calculated according to the quality factor and the scale transformation coefficient, and the calculation formula is:

[0127]

[0128] Where J represents the number of decomposition layers of the filter bank; N is the length of the spectrum distribution; round(·) is the rounding function;

[0129] A J-layer filter bank is formed by using low-pass filters and high-pass filters, wherein according to the j-th layer high-pass filter H 0,j (k) and the j-th low-pass filter H 1,j(k), forming the j-th layer filter; where j ranges from 1 to J.

[0130] In a possible design, the calculation module 202 is specifically used to: 0,j (k) and the j-th low-pass filter H 1,j The calculation formula of (k) is:

[0131]

[0132]

[0133]

[0134]

[0135]

[0136]

[0137] Wherein, θ(k) and θ(Nk) are the transition frequency band functions of the filter; round(·) is the floor function; P(j) is the passband of the j-th filter, S(j) is the cutoff frequency band of the j-th filter, and T(j) is the transition frequency band of the j-th filter; α and β represent the scaling coefficients; and N is the length of the spectrum distribution.

[0138] In one possible design, the calculation module 202 is specifically used to: let the spectrum distribution be the initial input V0(0) of the J-layer filter group, and calculate the sub-band signals output by the J-layer filter group in sequence; and calculate the sub-band signal energy sequence according to the sub-band signal V1(j) output by the j-th layer low-pass filter.

[0139] In a possible design, the calculation module 202 is specifically used for: the calculation formulas of the sub-band signal V1(j) output by the j-th layer low-pass filter are respectively:

[0140] V1(j)=V1(j-1)·H 1,j j=1,2,…,J

[0141] Among them, H 1，j represents the j-th low-pass filter.

[0142] In a possible design, the construction module 203 is specifically used to sequentially calculate the bidirectional transfer entropies corresponding to J elements in the sub-band signal energy sequence E and the historical sub-band signal energy sequence E', wherein the calculation formula for the bidirectional transfer entropy of the j-th element is:

[0143]

[0144]

[0145] Where T represents the bidirectional transfer entropy; h represents the entropy rate; p represents the probability; and are s-order and r-order Markov processes respectively, and E' j,t+1 ={E' j,t-s+1 ,…,E' j,t}and The difference of the bidirectional transfer entropy is calculated.

[0146] In a possible design, the above-mentioned determination module 204 is specifically used to calculate the transfer entropy change rate η according to the sub-band signal energy sequence and the main factor band signal energy sequence, and the calculation formula is:

[0147]

[0148] Where T represents the bidirectional transfer entropy, E j represents the jth element in the sub-band signal energy sequence, E j ' represents the jth element in the historical sub-band signal energy sequence, and w represents the number of main sub-band signal energies.

[0149] In one possible design, the above-mentioned judgment module 204 includes a state judgment module, which is specifically used to: when the transfer entropy change rate is greater than a preset threshold, it is judged that the transient mechanical state of the transformer winding has changed; when the transfer entropy change rate is less than or equal to the preset threshold, it is judged that the transient mechanical state of the transformer winding has not changed.

[0150] Based on the above device, by calculating the difference between the bidirectional transfer entropy between the sub-band signal energy sequence output by the J-layer filter group of the spectrum distribution of the current transient vibration signal and the historical sub-band signal energy sequence obtained according to the historical transient vibration signal, the main factor frequency band signal energy sequence is constructed according to the difference in bidirectional transfer entropy, and then the transfer entropy change rate is calculated according to the sub-band signal energy sequence and the main factor frequency band signal energy sequence, and the transient mechanical state of the transformer winding is judged according to the transfer entropy change rate. By obtaining the transfer entropy change rate through the difference in bidirectional transfer entropy between the sub-band signal energy sequence and the historical sub-band signal energy sequence, the transient mechanical state of the transformer winding before and after can be compared efficiently and accurately, thereby effectively judging the transient mechanical state of the transformer winding under short-circuit impact.

[0151] Figure 3 FIG. 1 shows an internal structure diagram of a computer device in an embodiment. The computer device may be a terminal or a server. Figure 3As shown, the computer device includes a processor, a memory and a network interface connected via a system bus. The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program. When the computer program is executed by the processor, the processor may execute each step of the above method. The internal memory may also store a computer program. When the computer program is executed by the processor, the processor may execute each step of the above method. Those skilled in the art will understand that Figure 3 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0152] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes each step of the above method.

[0153] In one embodiment, a computer-readable storage medium is provided, which stores a computer program. When the computer program is executed by a processor, the processor executes each step of the above method.

[0154] 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).

[0155] 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.

[0156] 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 monitoring the transient mechanical state of a transformer winding, characterized in that: The method comprises: Collecting a current transient vibration signal when the transformer is subjected to a short-circuit impact, normalizing the current transient vibration signal, and performing a discrete Fourier transform on the normalized current transient vibration signal to obtain a frequency spectrum distribution of the normalized current transient vibration signal; Design a J-layer filter bank according to the frequency spectrum distribution, and calculate a sub-band signal energy sequence output by the J-layer filter bank of the frequency spectrum distribution; Calculating the difference in bidirectional transfer entropy between the sub-band signal energy sequence and the historical sub-band signal energy sequence, and constructing a main factor band signal energy sequence according to the difference in bidirectional transfer entropy; wherein the historical sub-band signal energy sequence is a sub-band signal energy sequence obtained according to a historical transient vibration signal obtained before the current transient vibration signal; Calculating the transfer entropy change rate according to the sub-band signal energy sequence and the main factor frequency band signal energy sequence, and judging the transient mechanical state of the transformer winding according to the transfer entropy change rate; The calculating the difference between the bidirectional transfer entropy of the sub-band signal energy sequence and the historical sub-band signal energy sequence comprises: The bidirectional transfer entropies corresponding to the J elements in the sub-band signal energy sequence E and the historical sub-band signal energy sequence E' are calculated in sequence, wherein the calculation formula for the bidirectional transfer entropy of the j-th element is: Where T represents the bidirectional transfer entropy; h represents the entropy rate; p represents the probability; and are s-order and r-order Markov processes respectively, and E j ' ,t+1 ={E j ' ,t-s+1 ,…,E j ' ,t }and The value of j ranges from 1 to J; Calculating the difference of the bidirectional transfer entropy; The calculating the transfer entropy change rate according to the sub-band signal energy sequence and the main factor frequency band signal energy sequence comprises: The calculation formula for calculating the transfer entropy change rate η according to the sub-band signal energy sequence and the main factor band signal energy sequence is: Where T represents the bidirectional transfer entropy, E j represents the jth element in the sub-band signal energy sequence, E j ' represents the jth element in the historical sub-band signal energy sequence, and w represents the number of main sub-band signal energy sequences.

2. The method according to claim 1, characterized in that The designing of a J-layer filter bank according to the frequency spectrum distribution comprises: The quality factor and the scale transformation coefficient are calculated according to the spectrum distribution, and the calculation formula is: Q=f / BW Wherein, Q represents the quality factor; f refers to 100 Hz in the spectrum distribution; BW refers to the 3 dB bandwidth corresponding to the amplitude of the 100 Hz component; α and β represent the scaling coefficients; The number of decomposition layers of the filter bank is calculated according to the quality factor and the scale transformation coefficient, and the calculation formula is: Where J represents the number of decomposition layers of the filter bank; N is the length of the spectrum distribution; round(·) is the rounding function; A J-layer filter bank is formed by using low-pass filters and high-pass filters, wherein according to the j-th layer high-pass filter H 0,j (k) and the j-th low-pass filter H 1,j (k), forming the j-th layer filter; where j ranges from 1 to J.

3. The method according to claim 2, characterized in that The calculating of the sub-band signal energy sequence output by the J-layer filter bank of the frequency spectrum distribution comprises: Let the frequency spectrum distribution be the initial input V0(0) of the J-layer filter bank, and calculate the sub-band signals output by the J-layer filter bank in sequence; According to the sub-band signal V1(j) output by the j-th layer low-pass filter, a sub-band signal energy sequence is calculated.

4. The method according to claim 3, characterized in that: The calculation formulas of the sub-band signal V1(j) output by the j-th layer low-pass filter are respectively: V1(j)=V1(j-1)·H 1，j Among them, H 1，j Represents the j-th low-pass filter; the value of j is 1 to J.

5. The method according to claim 2, characterized in that: The j-th high-pass filter H 0,j (k) and the j-th low-pass filter H 1,j The calculation formula of (k) is: Wherein, θ(k) and θ(Nk) are the transition frequency band functions of the filter; round(·) is the rounding function; P(j) is the passband of the j-th filter, S(j) is the cutoff frequency band of the j-th filter, and T(j) is the transition frequency band of the j-th filter; α and β represent the scaling coefficients; N is the length of the spectrum distribution; and j ranges from 1 to J.

6. The method according to claim 1, characterized in that The step of determining the transient mechanical state of the transformer winding according to the transfer entropy change rate comprises: When the transfer entropy change rate is greater than a preset threshold, it is determined that the transient mechanical state of the transformer winding has changed; When the transfer entropy change rate is less than or equal to a preset threshold, it is determined that the transient mechanical state of the transformer winding has not changed.

7. A transformer winding transient mechanical state monitoring device, characterized in that: The device comprises: An acquisition module is used to collect a current transient vibration signal when the transformer is subjected to a short-circuit shock, normalize the current transient vibration signal, and perform a discrete Fourier transform on the normalized current transient vibration signal to obtain a frequency spectrum distribution of the normalized current transient vibration signal; A calculation module is used to design a J-layer filter group according to the frequency spectrum distribution, and calculate the sub-band signal energy sequence output by the J-layer filter group of the frequency spectrum distribution; A construction module is used to calculate the difference between the bidirectional transfer entropy of the sub-band signal energy sequence and the historical sub-band signal energy sequence, and construct the main factor band signal energy sequence according to the difference between the bidirectional transfer entropy; sequentially calculate the bidirectional transfer entropy corresponding to J elements in the sub-band signal energy sequence E and the historical sub-band signal energy sequence E', wherein the calculation formula of the bidirectional transfer entropy of the jth element is: Where T represents the bidirectional transfer entropy; h represents the entropy rate; p represents the probability; and are s-order and r-order Markov processes respectively, and E j ' ,t+1 ={E j ' ,t-s+1 ,…,E j ' ,t }and The value of j ranges from 1 to J; the difference of the bidirectional transfer entropy is calculated; A discrimination module is used to calculate the transfer entropy change rate according to the sub-band signal energy sequence and the main factor frequency band signal energy sequence, and discriminate the transient mechanical state of the transformer winding according to the transfer entropy change rate; the calculation formula for calculating the transfer entropy change rate η according to the sub-band signal energy sequence and the main factor frequency band signal energy sequence is: Where T represents the bidirectional transfer entropy, E j represents the jth element in the sub-band signal energy sequence, E j ' represents the jth element in the historical sub-band signal energy sequence, and w represents the number of main sub-band signal energy sequences.

8. The device according to claim 7, characterized in that The discrimination module comprises: State judgment module: when the transfer entropy change rate is greater than a preset threshold, it is judged that the transient mechanical state of the transformer winding has changed; when the transfer entropy change rate is less than or equal to the preset threshold, it is judged that the transient mechanical state of the transformer winding has not changed.

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