1. A circuit breaker fault diagnosis method based on vibration signal characteristic entropy fusion is characterized by comprising the following steps:

acquiring a vibration signal of a circuit breaker, and performing Empirical Mode Decomposition (EMD) on the vibration signal to obtain an intrinsic mode IMF component sequence;

calculating two groups of characteristic entropies of the vibration signal according to the IMF component sequence, wherein the two groups of characteristic entropies comprise one group of characteristic entropies consisting of energy entropies, singular entropies and cross-correlation entropies and the other group of characteristic entropies consisting of sample entropies, approximate entropies and fuzzy entropies;

respectively combining the two groups of characteristic entropies into characteristic entropy vectors, and performing characteristic entropy fusion on all the characteristic entropy vectors to obtain fusion characteristics;

and obtaining a fault diagnosis result of the circuit breaker by adopting a fault diagnosis algorithm according to the fusion characteristics.

2. The method according to claim 1, wherein the performing an Empirical Mode Decomposition (EMD) decomposition on the vibration signal to obtain a sequence of Intrinsic Mode (IMF) components comprises:

obtaining an initial mean value m of upper and lower envelope lines of a vibration signal x (t) of the circuit breaker₁₀(t), then, the original signal x (t) and the envelope mean m are obtained₁₀(t) a difference of 0 th component h₁₀(t), determining the component h₁₀(t) whether the IMF component condition is satisfied, if not, continuing to calculate until the kth time satisfies the IMF component condition, and obtaining a component h at the moment_1kAnd (t) taking the obtained IMF component as an original signal, and if the decomposition is continued, continuing to repeat the operation by taking the obtained IMF component as the original signal to obtain a series of IMF components.

3. The method according to claim 2, wherein the energy entropy, singular entropy and cross-correlation entropy are calculated by:

according to the definition of energy, let the time series of an IMF component be x (t), the sequence length be n, the IMF component sequence has energy as shown in formula (2):

let the k component imf of the sample_kHaving an energy of E_kCalculating E according to equation (2)_kAs shown in formula (3).

Defining the normalized denominator E as:

normalized per energy E_kThe ratio of/E to the total normalized energy is P_kThen the probability feature vector T₁Comprises the following steps:

T₁＝[P₁，P₂,...，P₆] (5)

according to the definition of formula (1), the energy entropy V_NEEComprises the following steps:

let two orthogonal matrices U and V satisfy U^TTaking the matrix a as the first 6 IMF components, that is, the dimension of the matrix a is 6, then the singular values are the diagonal elements of the matrix Λ:

sequentially calculating singular values lambda of the first 6 IMF components after EMD decomposition of the original signal according to the formula (7)_iEach singular value λ_iThe ratio of the square root to the root of all singular values is q_iThen there is normalized singular value eigenvector T₂Comprises the following steps:

T₂＝[q₁，q₂,…，q₆] (13)

then, according to the definition of equation (1), the singular entropy V_NSDComprises the following steps:

the cross-correlation entropy calculation method is obtained according to the correlation coefficient of each IMF component and the original signal, and the Pearson correlation coefficient corr of the kth IMF component and the original signal is calculated_kThe corr_kIs x (t) imf at the center frequency_k(t) probability distribution, and obtaining the cross-correlation entropy V of the sample according to the formula (10)_NMIComprises the following steps:

4. the method of claim 2, wherein the sample entropy, approximate entropy and fuzzy entropy are calculated by:

assuming that the time series of IMF components is x (t), the length is N, the embedding dimension is m, i is an integer from 1 to N-m +1, a set of sub-sequence vectors of dimensions is defined as shown in equation (16):

X(i)＝[x(i)，x(i+1)，...，x(i+m-1)]i＝1～N-m+1 (16)

defining the distance dist between any two subsequences as the one with the largest difference value of the corresponding elements, as shown in formula (17), wherein k is an integer value obtained by subtracting 1 from 0 to the specified embedding dimension m;

the similarity ratio is calculated according to the formula (18)Comprises the following steps:

continuing to calculate the transition value Φ for the given embedding dimension m according to equation (19)^m(r) has:

repeating the above steps to calculate phi of m +1^m+1(r), under the condition of specifying the sequence length N, obtaining the approximate entropy ApEn (m, r, N), and the calculation formula is shown in the formula (15).

ApEn(m，r，N)＝Φ^m(r)-Φ^m+1(r) (20)

For the sample entropy, it is only necessary to change the expressions (18) to (20) to the expressions (21) to (23), and the expression (21) has the same meaning as the expression (18) and is a similarity ratio; the formula (22) has the same meaning as the formula (19) and is a transition value of the embedding dimension m; according to the new formulas (21) to (22), the sample entropy SE (m, r, N) is calculated according to formula (23):

the meanings of the formula (24) and the formula (25) are unchanged, the meanings are respectively a similarity proportion and a transition value of the embedding dimension m, and the fuzzy entropy FE (m, N, r, N) is obtained through calculation according to the formula (26):

FE(m，n，r，N)＝lnΦ^m(n，r)-lnΦ^m+1(n，r) (26)。

5. the method according to claim 4, wherein the combining the two sets of feature entropies into feature entropy vectors, and performing feature entropy fusion on all feature entropy vectors to obtain fused features comprises:

setting fault types of the circuit breaker to be six types including false switching-on, incomplete switching-off, jamming of an operating mechanism, jamming of a transmission gear, jamming of an energy storage spring and loosening of a base bolt, wherein the circuit breaker has 8 working states in total under the two conditions of normal switching-on and normal switching-off, each working state respectively collects multiple groups of waveform data, each group of waveforms respectively obtain energy entropy, singular entropy, cross-correlation entropy, approximate entropy, sample entropy and fuzzy entropy, the entropies form characteristic entropy vectors, all the characteristic entropy vectors form a characteristic matrix, normalization processing is carried out on the input matrix, and the average value of corresponding dimensions is subtracted from each characteristic of the characteristic matrix; then, a covariance matrix is calculated, and diagonal elements and off-diagonal elements respectively represent an auto-covariance coefficient and a cross-covariance coefficient; then calculating eigenvectors and eigenvalues of the covariance matrix, sorting the eigenvectors and the eigenvalues from large to small, taking the eigenvectors corresponding to the first k largest eigenvalues as a new orthogonal eigenvector matrix, and taking the new orthogonal eigenvector matrix as fusion characteristics.

6. The method of claim 5, wherein obtaining the fault diagnosis result of the circuit breaker by using a fault diagnosis algorithm according to the fused feature comprises:

the method comprises the steps of presetting six fault types of the circuit breaker and two working states of normal closing and normal opening in a Support Vector Machine (SVM) and a multilayer sensing Machine (MLP), inputting the fusion characteristics into the SVM and the MLP, respectively carrying out fault diagnosis by the Support Vector Machine (SVM) and the multilayer sensing Machine (MLP), respectively outputting fault diagnosis results of the circuit breaker, and then integrating the two fault diagnosis results to obtain a final fault diagnosis result of the circuit breaker.

Background

The circuit breaker is of a plurality of types and is widely applied to urban rail systems. The fault diagnosis technology of the circuit breaker mainly comprises off-line detection, the off-line detection mainly comprises regular maintenance and preventive maintenance, and the detected circuit breaker parameters generally comprise contact stroke, contact movement time, contact movement speed, contact surface resistance, resistance of a switching-on and switching-off coil loop, sound signals, contact abrasion and the like. Because the detection items are too many and time-consuming and labor-consuming, a new mode, namely a state maintenance technology, is urgently needed at present. One of the advantages of the state maintenance is high efficiency, only hardware such as a detection sensor and an upper computer needs to be installed, the fault type and the fault position of the circuit breaker can be rapidly positioned by a background program, major accidents can be avoided in advance compared with offline detection, and the stability of a power system is improved.

The parameters of the existing circuit breaker for state maintenance are mainly 3, namely mechanical vibration, opening and closing coil current and energy storage motor current. Since the mechanical fault occurrence rate is much higher than the electrical fault, the vibration signal is still the main condition monitoring parameter of the circuit breaker. At present, a method for detecting a vibration signal of a circuit breaker in the prior art includes: there are time-domain, frequency-domain and time-frequency methods, such as fourier transform, wavelet analysis, etc., but these methods have their own limitations. The time domain method has good detection effect on stationary signals, but is not suitable for non-stationary vibration signals; the fourier transform cannot reflect local features of non-stationary signals; wavelet analysis has no uniform standard for selection of wavelet basis, decomposition level and threshold, and is not beneficial to popularization. The invention is based on the theory of entropy, processes the non-stable nonlinear signal, has the advantages of higher self-adaptive capacity and multi-resolution, can give consideration to time domain and frequency domain characteristics, local and global characteristics, is also suitable for fault diagnosis of different types of circuit breakers and diagnosis of vibration fault types of other electrical equipment, and can be popularized.

Disclosure of Invention

The embodiment of the invention provides a breaker fault diagnosis method based on vibration signal characteristic entropy fusion, so as to effectively diagnose the fault of a breaker.

In order to achieve the purpose, the invention adopts the following technical scheme.

A breaker fault diagnosis method based on vibration signal characteristic entropy fusion comprises the following steps:

acquiring a vibration signal of a circuit breaker, and performing Empirical Mode Decomposition (EMD) on the vibration signal to obtain an intrinsic mode IMF component sequence;

calculating two groups of characteristic entropies of the vibration signal according to the IMF component sequence, wherein the two groups of characteristic entropies comprise one group of characteristic entropies consisting of energy entropies, singular entropies and cross-correlation entropies and the other group of characteristic entropies consisting of sample entropies, approximate entropies and fuzzy entropies;

respectively combining the two groups of characteristic entropies into characteristic entropy vectors, and performing characteristic entropy fusion on all the characteristic entropy vectors to obtain fusion characteristics;

and obtaining a fault diagnosis result of the circuit breaker by adopting a fault diagnosis algorithm according to the fusion characteristics.

Preferably, the performing empirical mode decomposition EMD decomposition on the vibration signal to obtain an intrinsic mode IMF component sequence includes:

obtaining an initial mean value m of upper and lower envelope lines of a vibration signal x (t) of the circuit breaker₁₀(t), then, the original signal x (t) and the envelope mean m are obtained₁₀(t) a difference of 0 th component h₁₀(t), determining the component h₁₀(t) whether the IMF component condition is satisfied, if not, continuing to calculate until the kth time satisfies the IMF component condition, and obtaining a component h at the moment_1kAnd (t) taking the obtained IMF component as an original signal, and if the decomposition is continued, continuing to repeat the operation by taking the obtained IMF component as the original signal to obtain a series of IMF components.

Preferably, the method for calculating the energy entropy, the singular entropy and the cross-correlation entropy comprises the following steps:

according to the definition of energy, let the time series of an IMF component be x (t), the sequence length be n, the IMF component sequence has energy as shown in formula (2):

let the k component imf of the sample_kHaving an energy of E_kCalculating E according to equation (2)_kAs shown in formula (3).

Defining the normalized denominator E as:

normalized per energy E_kThe ratio of/E to the total normalized energy is P_kThen the probability feature vector T₁Comprises the following steps:

T₁＝[P₁,P₂,...,P₆] (5)

according to the definition of formula (1), the energy entropy V_NEEComprises the following steps:

let two orthogonal matrices U and V satisfy U^THV ═ Λ, take the a matrix as the first 6 IMF components, i.e., the dimension of the a matrix is 6, then the singular values are the diagonal elements of the Λ matrix:

sequentially calculating singular values lambda of the first 6 IMF components after EMD decomposition of the original signal according to the formula (7)_iEach singular value λ_iThe ratio of the square root to the root of all singular values is q_iThen there is normalized singular value eigenvector T₂Comprises the following steps:

T₂＝[q₁,q₂,...,q₆] (13)

then, according to the definition of equation (1), the singular entropy V_NSDComprises the following steps:

the cross-correlation entropy calculation method is obtained according to the correlation coefficient of each IMF component and the original signal, and the k IMF component and the original signal are calculatedPearson's correlation coefficient corr_kThe corr_kIs x (t) imf at the center frequency_k(t) probability distribution, and obtaining the cross-correlation entropy V of the sample according to the formula (10)_NMIComprises the following steps:

preferably, the sample entropy, approximate entropy and fuzzy entropy are calculated by the following method:

assuming that the time series of IMF components is x (t), the length is N, the embedding dimension is m, i is an integer from 1 to N-m +1, a set of sub-sequence vectors of dimensions is defined as shown in equation (16):

X(i)＝[x(i),x(i+1),...,x(i+m-1)] i＝1～N-m+1 (16)

defining the distance dist between any two subsequences as the one with the largest difference value of the corresponding elements, as shown in formula (17), wherein k is an integer value obtained by subtracting 1 from 0 to the specified embedding dimension m;

the similarity ratio is calculated according to the formula (18)Comprises the following steps:

continuing to calculate the transition value Φ for the given embedding dimension m according to equation (19)^m(r) has:

repeating the above steps to calculate phi of m +1^m+1(r), under the condition of specifying the sequence length N, obtaining the approximate entropy ApEn (m, r, N), and the calculation formula is shown in the formula (15).

ApEn(m,r,N)＝Φ^m(r)-Φ^m+1(r) (20)

For the sample entropy, it is only necessary to change the expressions (18) to (20) to the expressions (21) to (23), and the expression (21) has the same meaning as the expression (18) and is a similarity ratio; the formula (22) has the same meaning as the formula (19) and is a transition value of the embedding dimension m; according to the new formulas (21) to (22), the sample entropy SE (m, r, N) is calculated according to formula (23):

the meanings of the formula (24) and the formula (25) are unchanged, the meanings are respectively a similarity proportion and a transition value of the embedding dimension m, and the fuzzy entropy FE (m, N, r, N) is obtained through calculation according to the formula (26):

FE(m，n，r，N)＝lnΦ^m(n，r)-lnΦ^m+1(n，r) (26)。

preferably, the combining the two groups of feature entropies into feature entropy vectors respectively, and performing feature entropy fusion on all the feature entropy vectors to obtain fusion features includes:

setting fault types of the circuit breaker to be six types including false switching-on, incomplete switching-off, jamming of an operating mechanism, jamming of a transmission gear, jamming of an energy storage spring and loosening of a base bolt, wherein the circuit breaker has 8 working states in total under the two conditions of normal switching-on and normal switching-off, each working state respectively collects multiple groups of waveform data, each group of waveforms respectively obtain energy entropy, singular entropy, cross-correlation entropy, approximate entropy, sample entropy and fuzzy entropy, the entropies form characteristic entropy vectors, all the characteristic entropy vectors form a characteristic matrix, normalization processing is carried out on the input matrix, and the average value of corresponding dimensions is subtracted from each characteristic of the characteristic matrix; then, a covariance matrix is calculated, and diagonal elements and off-diagonal elements respectively represent an auto-covariance coefficient and a cross-covariance coefficient; then calculating eigenvectors and eigenvalues of the covariance matrix, sorting the eigenvectors and the eigenvalues from large to small, taking the eigenvectors corresponding to the first k largest eigenvalues as a new orthogonal eigenvector matrix, and taking the new orthogonal eigenvector matrix as fusion characteristics.

Preferably, the obtaining of the fault diagnosis result of the circuit breaker by using the fault diagnosis algorithm according to the fusion feature includes:

the method comprises the steps of presetting six fault types of the circuit breaker and two working states of normal closing and normal opening in a Support Vector Machine (SVM) and a multilayer sensing Machine (MLP), inputting the fusion characteristics into the SVM and the MLP, respectively carrying out fault diagnosis by the Support Vector Machine (SVM) and the multilayer sensing Machine (MLP), respectively outputting fault diagnosis results of the circuit breaker, and then integrating the two fault diagnosis results to obtain a final fault diagnosis result of the circuit breaker.

According to the technical scheme provided by the embodiment of the invention, the method is suitable for extracting the characteristics of the vibration signal of the circuit breaker under the actual condition and is also suitable for extracting the characteristics of the vibration signal of the electrical equipment in the train. The vibration signal characteristic method provided by the invention is simple and efficient, improves the identification rate of fault diagnosis of the circuit breaker, and has important significance for ensuring the safe operation of an urban rail system.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a flowchart illustrating an EMD (Empirical Mode Decomposition) Decomposition process according to an embodiment of the present invention;

FIG. 2 is a flowchart of computing energy entropy, singular entropy and cross-correlation entropy according to an embodiment of the present invention;

FIG. 3 is a flowchart of calculating approximate entropy, sample entropy and fuzzy entropy according to an embodiment of the present invention;

fig. 4 is a flowchart of feature entropy fusion of a circuit breaker according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a construction process of an SVM optimal model provided by the embodiment of the present invention;

fig. 6 is a schematic diagram of a network structure of a multi-layer perceptron MLP algorithm provided in an embodiment of the present invention;

fig. 7 is a schematic diagram of a construction process of an optimal model of a multi-layer perceptron MLP according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or coupled. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

For the convenience of understanding the embodiments of the present invention, the following description will be further explained by taking several specific embodiments as examples in conjunction with the drawings, and the embodiments are not to be construed as limiting the embodiments of the present invention.

Aiming at the defects in the prior art, the embodiment of the invention provides a breaker fault diagnosis method based on vibration signal characteristic entropy fusion, the diagnosed fault types comprise five conditions of false switching-on, incomplete switching-off, jamming of an energy storage spring, jamming of an operating mechanism and bolt looseness, and compared with the traditional method, the method has self-adaption and multi-resolution, and the accuracy rate of breaker fault diagnosis and prediction is improved.

The vibration signal characteristic entropy in the embodiment of the invention comprises two groups: one group includes: energy entropy, singular entropy and cross-correlation entropy; another group includes: the method comprises the steps of calculating sample entropy, approximate entropy and fuzzy entropy, and calculating two groups of characteristic entropies by using different theoretical methods respectively, and finally performing characteristic entropy fusion dimensionality reduction by adopting a principal component dimensionality reduction technology so as to perform fault diagnosis on the circuit breaker.

Fig. 1 is an EMD decomposition flowchart according to an embodiment of the present invention. The process decomposes a vibration signal x (t) of a non-stationary nonlinear circuit breaker into IMF (Intrinsic Mode function) components with different scales, and can reflect the frequency distribution of an original signal through the central frequency of the IMF components, which is a necessary condition for obtaining information entropy through subsequent calculation, and the information entropy can further amplify the central frequency characteristics of the IMF components to distinguish different fault types for diagnosis. The types of information entropy include energy entropy, singular entropy, and cross-correlation entropy.

The process of EMD decomposition mainly comprises five steps, wherein the first step is to obtain the initial mean value m of the upper envelope and the lower envelope of the vibration signal x (t) of the circuit breaker₁₀(t) then calculating the original signal x (t) and the envelope mean m₁₀(t) a difference of 0 th component h₁₀(t) then judging the component h₁₀(t) whether the IMF component condition is satisfied, if not, continuing to calculate until the kth time satisfies the IMF component condition, and then obtaining a component h_1kAnd (t) is the obtained IMF component. If the decomposition is continued, the obtained IMF component is taken as an original signal, and the operations are repeated, so that a series of IMF components can be obtained finally.

Fig. 2 is a flowchart for calculating information entropy according to the present invention. The method for calculating the energy entropy, the singular entropy and the cross-correlation entropy is a calculation formula based on an information entropy theory, and is shown as a formula (1):

where entrypy is the information entropy, i.e. energy entropy, singular entropy or cross-correlation entropy, and x is assumed₁,x₂,…x_nIs a system with n random states, which can be arbitrary, then P (x)_i) For the probability corresponding to each state, the information entropy value describing the system can be obtained by calculating the probability corresponding to the states according to the formula (1).

The formula for calculating the information entropy is shown as formula (1), and the corresponding energy entropy, singular entropy and cross-correlation entropy can be obtained according to formulas (2) to (10). The energy entropy calculation method is used for calculating energy of different IMF components after empirical mode decomposition, each IMF component has a specific central frequency range, and the energy distribution of the vibration signal depends on the distribution of the central frequency of each IMF component. According to the definition of energy, if the time sequence of an IMF component is x (t), and the sequence length is n, the energy of the IMF component sequence is shown in formula (2).

Let the k component imf of the sample_kHaving an energy of E_kE can be calculated from equation (2)_kAs shown in formula (3).

In general, the energies of different IMF components may differ too much, and normalization is required, defining a normalized denominator E as

Normalized per energy E_kThe ratio of/E to the total normalized energy is P_kThen there is a probability feature vector T₁Is composed of

T₁＝[P₁,P₂,...,P₆] (5)

According to the definition of formula (1), the energy entropy V_NEEIs composed of

The singular entropy calculation method is obtained by singular value decomposition, and two orthogonal matrixes U and V are set to meet the requirement of U lambada V^TTaking A matrix as the first 6 IMsThe F component, i.e., the dimension of the a matrix is 6, then the singular values are the diagonal elements of the Λ matrix, which can be written as:

the diagonal elements are singular values to be found.

Sequentially calculating singular values lambda of the first 6 IMF components after EMD decomposition of the original signal according to the formula (7)_i。

The singular value decomposition process is described as follows, for the matrix a, the transpose of a and a is subjected to matrix multiplication, so that a square matrix of n × n is obtained, the square matrix can be subjected to eigen decomposition, and the obtained eigenvalue and eigenvector satisfy the formula (8), wherein the eigenvector is called as a left eigenvector.

(AA^T)v_i＝λ_iv_i (8)

In the same way, the transpose of A and A can be subjected to matrix multiplication, a square matrix can be obtained for feature decomposition, and the obtained feature vector is called as a right feature vector.

(A^TA)u_i＝λ_iu_i (9)

For H, except for singular values on the diagonal, other positions are all 0, so that the matrix H can be solved by only requiring each singular value sigma, and the principle is shown in a formula (10).

Then, in effect, A^TA is the orthogonal matrix V, AA^TFor the orthogonal matrix U sought, the procedure for the proof is as follows.

Therein proving the use of U^UI and Λ^TA can be seen ═ Λ^TA certainty of the feature vector compositionThat is the V matrix in our SVD, and similarly the AA can also be demonstrated^TIs the U matrix.

Further, we can see that the eigenvalue matrix is equal to the square of the singular value matrix, i.e. the eigenvalues and singular values satisfy the following equation (12), i.e. we can eliminate the use ofTo calculate the singular value, it is also possible to calculate A^TAnd taking a square root of the eigenvalue of the A to solve the singular value.

The 6 singular values can be solved according to the above equations (7) to (12).

Then each singular value λ_iThe ratio of the square root to the root of all singular values is q_iThen there is a normalized singular value eigenvector T₂Comprises the following steps:

T₂＝[q₁,q₂,...,q₆] (13)

then, according to the definition of equation (1), the singular entropy V_NSDComprises the following steps:

the cross-correlation entropy is calculated according to the correlation coefficient of each IMF component and the original signal, and the Pearson correlation coefficient obtained by the method can be understood as x (t) IMF at the central frequency_k(t) probability distribution, where the cross-correlation entropy V of the samples is obtained according to equation (1)_NMIComprises the following steps:

wherein, corr_kFor each IMF component, the pearson correlation coefficient with the original signal.

Fig. 3 is a flowchart of an algorithm for calculating the approximate entropy, the sample entropy, and the fuzzy entropy according to equations (16) - (26), where the method for calculating the approximate entropy, the sample entropy, and the fuzzy entropy is based on sequence similarity, and follows the time sequence x (t) of the above-mentioned IMF component, where the length is N, the embedding dimension is m, and i is an integer from 1 to N-m +1, then a set of dimensional subsequence vectors may be defined first, as shown in equation (16).

X(i)＝[x(i),x(i+1),...,x(i+m-1)] i＝1～N-m+1 (16)

The distance dist between any two subsequences is defined as the one with the largest difference between their corresponding elements, as shown in equation (17), where k is an integer value from 0 to the specified embedding dimension m minus 1.

Then, the similarity ratio is calculated according to the formula (18)Comprises the following steps:

continuing to calculate the transition value Φ for the given embedding dimension m according to equation (19)^m(r) has:

repeating the above steps to calculate phi of m +1^m+1(r), under the condition of specifying the sequence length N, the approximate entropy ApEn (m, r, N) can be obtained, and the calculation formula is shown as the formula (20).

ApEn(m,r,N)＝Φ^m(r)-Φ^m+1(r) (20)

The sample entropy may be changed from expressions (18) to (20) to expressions (21) to (23). The formula (21) has the same meaning as the formula (18) and is a similarity ratio; the formula (22) has the same meaning as the formula (19) and is a transition value of the embedding dimension m; according to the new formulas (21) to (23), SE (m, r, N) obtained by the formula (23) is called sample entropy, and the sample entropy is improved relative to the approximate entropy of the formula (20).

The approximate entropy and the sample entropy are both binary classifiers essentially, have the property of a step function, the fuzzy entropy introduces an exponential function as a fuzzy function, has continuous smooth property, can better describe the similarity of waveforms, and correspondingly, the calculation formula is changed into the formulas (24) to (26), the meanings of the formula (24) and the formula (25) are not changed, and are respectively a similarity proportion and a transition value of an embedding dimension m, and FE (m, N, r, N) obtained by the formula (26) is fuzzy entropy.

FE(m，n，r，N)＝lnΦ^m(n，r)-lnΦ^m+1(n，r) (26)

And then fusing all the characteristic entropies obtained by calculation of the formulas, adopting a principal component dimensionality reduction technology, obtaining energy entropy, singular entropy and cross-correlation entropy according to the process of figure 2, obtaining sample entropy, approximate entropy and fuzzy entropy by calculation according to the process of figure 3, combining the two groups of characteristic entropies into a characteristic entropy vector, then carrying out characteristic entropy fusion, and finally obtaining data for a related algorithm of subsequent fault diagnosis.

Fig. 4 is a flowchart of feature entropy fusion of a circuit breaker according to an embodiment of the present invention. The diagnosed fault types of the circuit breaker comprise six types, namely false switching-on, incomplete switching-off, jamming of an operating mechanism, jamming of a transmission gear, jamming of an energy storage spring, loosening of a base bolt and the like, and the circuit breaker has 8 working states in total under the two conditions of normal switching-on and normal switching-off. Multiple sets of waveform data (30) are collected for each operating state, so a total of 240 sets of waveform data can be collected. Energy entropy, singular entropy, cross-correlation entropy, approximate entropy, sample entropy and fuzzy entropy can be obtained for each group of waveforms according to fig. 2 and fig. 3 respectively, the entropies form characteristic entropy vectors, then 240 groups of characteristic entropy vectors are counted, and all the characteristic entropy vectors form a characteristic matrix, namely the input of fig. 4 is a characteristic matrix of 240 × 6.

According to fig. 4, firstly, the input matrix is normalized, that is, each feature of the feature matrix is subtracted by the average value of the corresponding dimension; then, a covariance matrix is calculated, and diagonal elements and off-diagonal elements respectively represent an auto-covariance coefficient and a cross-covariance coefficient; then, eigenvectors and eigenvalues of the covariance matrix are calculated, the eigenvectors and the eigenvalues are ranked from large to small, the eigenvectors corresponding to the first k largest eigenvalues are used as a new orthogonal eigenvector matrix, and the k value can be determined according to the variance contribution rate. And taking the new orthogonal feature matrix as a fusion feature.

The k value determined by the present invention is 2, i.e. the output of fig. 4 is a feature matrix of 240 x 2. And then fault diagnosis is carried out according to two algorithms of the support vector machine SVM and the multilayer perceptron MLP, six fault types and two working states of normal closing and normal opening of the circuit breaker are preset in the support vector machine SVM and the multilayer perceptron MLP, the fusion characteristics are input into the support vector machine SVM and the multilayer perceptron MLP, fault diagnosis is carried out by the two algorithms of the support vector machine SVM and the multilayer perceptron MLP respectively, and fault diagnosis results of the circuit breaker are output respectively. And then, integrating the two fault diagnosis results to obtain a final fault diagnosis result of the circuit breaker.

The two types of algorithm models of the support vector machine SVM and the multi-layer perceptron MLP have similar training processes, which are respectively shown in FIG. 5 and FIG. 7. The diagnosed circuit breaker faults are 6 fault types of false switching-on, incomplete switching-off, jamming of a transmission mechanism, jamming of an operating mechanism, jamming of an energy storage spring and loosening of a base bolt.

Fig. 5 is a schematic diagram of a process for constructing an optimal model of a support vector machine SVM according to the present invention, where a selection of a kernel function is discussed first, then a test training set division method is discussed, and then a selection of a regularization coefficient and a test set proportion is discussed, and particularly, when the kernel function is not a linear kernel function, a kernel coefficient is discussed, and parameters of the optimal model of the SVM determined by the present invention are: the kernel function is a linear kernel function, the regularization coefficient is 0.1, the training test set division method is a leave-1 method (that is, 1 feature matrix of 240 × 2 is left as a test set each time, so the training times are 240 times in practice), the test set proportion is 0.3, and the kernel coefficient does not need to be considered.

Fig. 6 is a schematic diagram of a network structure of the MLP algorithm, where the number of neurons in the input layer is 2 (determined by the dimension of the output feature matrix in fig. 4 being equal to 2), the number of neurons in the first layer is 5, the number of neurons in the second layer is 2, and the number of neurons in the output layer is 8 (determined by 8 types of diagnosed 6 faults and 2 types of opening and closing in a normal state, which belong to 8 classification problems).

Fig. 7 is a schematic diagram of a construction process of an MLP optimal model of a multi-layer perceptron provided by the present invention, where selection of an activation function is discussed first, then selection of a weight optimizer is selected, and finally a regularization coefficient and a test set proportion are determined, and selection of a particular learning method, a learning rate, and a scaling index is discussed only when the weight optimizer is a gradient descent method, and parameters of the MLP optimal model determined by the present invention are: the activation function is Identity, the weight optimizer is quasi-Newton method Lbfgs, the regularization coefficient is 0.1, and the test set proportion is 0.3.

Optionally, the normalization reference of the obtained energy, singular value and correlation coefficient may be the sum of the square roots and the squares of all eigenvalues, or may be the sum of all eigenvalues.

Optionally, the proposed correlation coefficient calculation method may be a pearson correlation coefficient or a spearman correlation coefficient.

Alternatively, the proposed Singular Value Decomposition method may be a random SVD (Singular Value Decomposition) method or a truncated SVD method.

Optionally, the principal component dimensionality reduction may be kernel principal component analysis or sparse principal component analysis.

In summary, the embodiment of the invention provides an entropy-based method for extracting features of a vibration signal based on adaptive and multi-resolution technologies, considering the non-stationary nonlinearity of the vibration signal in actual measurement, aiming at the problem that the fault diagnosis rate of the circuit breaker at the present stage is not high. The method is suitable for feature extraction of the vibration signal of the circuit breaker under the actual condition and is also suitable for feature extraction of the vibration signal of the electrical equipment in the train. The vibration signal characteristic method provided by the invention is simple and efficient, improves the identification rate of fault diagnosis of the circuit breaker, and has important significance for ensuring the safe operation of an urban rail system.

The invention can effectively monitor the operation parameters of the breaker, can obtain the working state of the breaker without power-off maintenance, can give out early warning in advance, can quickly and accurately give out the possible fault types and the probability of the breaker, and can give out relevant reasonable measures such as switching, load shedding and the like, thereby effectively reducing the loss caused by power failure in a factory.

Those of ordinary skill in the art will understand that: the figures are merely schematic representations of one embodiment, and the blocks or flow diagrams in the figures are not necessarily required to practice the present invention.

From the above description of the embodiments, it is clear to those skilled in the art that the present invention can be implemented by software plus necessary general hardware platform. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which may be stored in a storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method according to the embodiments or some parts of the embodiments.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for apparatus or system embodiments, since they are substantially similar to method embodiments, they are described in relative terms, as long as they are described in partial descriptions of method embodiments. The above-described embodiments of the apparatus and system are merely illustrative, and the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.