Method, system and device for evaluating electrical fault diagnosability of three-phase asynchronous motor

Abstract

The invention discloses a three-phase asynchronous motor electrical fault diagnosability evaluation method, system and device, and relates to the field of fault diagnosis, and the method comprises the steps: obtaining a three-phase low-frequency current signal, a three-phase high-frequency current signal and a motor nameplate parameter of a three-phase asynchronous motor in an operation state; based on the low-frequency energy diagnosable index, the high-frequency energy diagnosable index, the low-frequency stability diagnosable index and the high-frequency stability diagnosable index, a low-frequency comprehensive diagnosable index and a high-frequency comprehensive diagnosable index are obtained, the low-frequency comprehensive diagnosable index is not smaller than a low-frequency threshold value, and a low-frequency fault can be diagnosed; the high-frequency comprehensive diagnosable index is not less than a high-frequency threshold, and the high-frequency fault can be diagnosed. The energy diagnosable index is positively correlated with the effective value of the current signal, the stability diagnosable index is negatively correlated with the jump times of the current signal, the two diagnosis indexes are comprehensively considered to reduce the influence of operation conditions such as motor load fluctuation on electrical fault diagnosis, and the reliability of electrical fault diagnosis of the motor is improved.

Description

Technical Field

[0001] The present invention relates to the field of fault diagnosis, and in particular to a method, system and device for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor. Background Art

[0002] The motor operation status assessment and fault diagnosis technology based on ESA (Electrical Signature Analysis) usually collects the three-phase current signal and three-phase voltage signal of the motor at the same time. The high-frequency current signal and the high-frequency current signal contain the operation status information of the drive, transmission and load components of the mechanical equipment, which can be used to identify the equipment failure mode. Ideally, the motor current signal is a standard 50Hz sine wave with only one peak in the spectrum. However, the distribution of the internal magnetic flux of the motor changes due to the presence of various mechanical and electrical faults in the actual industrial site. The current signal spectrum often shows many peaks, including current characteristics such as power frequency, harmonics, and sidebands. The analysis of these characteristics can effectively identify the electrical faults of the motor and some mechanical faults. However, the working current of the motor is also affected by the operating parameters, drive load, magnetic saturation and power quality. The load driven by the motor is the main factor affecting the current size. The larger the load, the greater the power required by the motor, so the working current will increase accordingly. ESA usually uses the relative change information of the current signal, which is easily affected by the operating parameters and load changes, resulting in inaccurate evaluation of the motor operation status. Summary of the invention

[0003] The purpose of the present invention is to provide a method, system and device for evaluating the diagnosability of electrical faults in a three-phase asynchronous motor. The higher the diagnosability, the higher the possibility that the electrical fault of the motor can be diagnosed, the factors caused by the load are eliminated, and the interference of the load is reduced.

[0004] In order to solve the above technical problems, the present invention provides a method for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor, comprising:

[0005] Acquire a three-phase low-frequency current signal, a three-phase high-frequency current signal and motor nameplate parameters of a three-phase asynchronous motor in a running state, wherein the frequencies of the three-phase low-frequency current signal and the three-phase high-frequency current signal are determined by a preset frequency range, and the motor nameplate parameters include rated operating parameters of the motor;

[0006] Determine a low-frequency energy diagnosable index and a high-frequency energy diagnosable index according to the three-phase low-frequency current signal, the three-phase high-frequency current signal and the motor nameplate parameter, wherein the energy diagnosable index is positively correlated with the effective value of the current signal;

[0007] Determining a low-frequency stability diagnosable index and a high-frequency stability diagnosable index according to the three-phase low-frequency current signal and the three-phase high-frequency current signal, wherein the stability diagnosable index is negatively correlated with the number of jumps of the current signal;

[0008] If the low-frequency comprehensive diagnosable index determined according to the low-frequency energy diagnosable index and the low-frequency stability diagnosable index is not less than the low-frequency threshold, it is determined that the low-frequency fault is diagnosable;

[0009] If the high-frequency comprehensive diagnosable index determined according to the high-frequency energy diagnosable index and the high-frequency stability diagnosable index is not less than the high-frequency threshold, it is determined that the high-frequency fault is diagnosable.

[0010] On the other hand, determining a high-frequency energy diagnosable index and a low-frequency energy diagnosable index according to the three-phase low-frequency current signal, the three-phase high-frequency current signal and the motor nameplate parameter includes:

[0011] Determining a low-frequency energy diagnosable index and a high-frequency energy diagnosable index according to a load factor, wherein the load factor is positively correlated with the values ​​of the three-phase low-frequency current signal and the three-phase high-frequency current signal;

[0012] The expression of the low-frequency energy diagnosable index is:

[0013] ;

[0014] The expression of the high-frequency energy diagnosable index is:

[0015] ;

[0016] in, It is a diagnostic indicator of low-frequency energy. is the load factor of the low-frequency current signal of phase A, is the load factor of the low-frequency current signal of phase B, is the load factor of the C-phase low-frequency current signal, is the load factor of the p-phase low-frequency current signal, p∈[A,B,C], For p, take the value of A, B or C The maximum value of A, B and C are the three phases of the current signal. It is a high-frequency energy diagnostic indicator. is the load factor of the high-frequency current signal of phase A, is the load factor of the high-frequency current signal of phase B, is the load factor of the C-phase high-frequency current signal, is the load factor of the p-phase high-frequency current signal, For p, take the value of A, B or C The maximum value of , m is the load factor threshold, and α is the energy parameter.

[0017] On the other hand, the process of determining the load factor includes:

[0018] The load factor of the three-phase low-frequency current signal is determined according to the effective value of the three-phase low-frequency current signal, the effective value of the three-phase high-frequency current signal and the motor nameplate parameters. The expression of the load factor is: ;

[0019] in, is the load factor of the p-phase f-frequency current signal, is the effective value of the p-phase f-frequency current signal, f∈[lf,hf], lf is the low frequency, hf is the high frequency, rms rc It is the rated current in the motor nameplate parameters.

[0020] On the other hand, the process of determining the effective value of the three-phase low-frequency current signal and the effective value of the three-phase high-frequency current signal includes:

[0021] According to the current effective value calculation relationship, three-phase low-frequency current signal , , And three-phase high-frequency current signal , and Determine the effective value of the three-phase low-frequency current signal separately , and And the effective value of the three-phase high-frequency current signal , and ;

[0022] Among them, the current effective value calculation relationship is: , N is the number of current signals, x i is the ith current signal.

[0023] On the other hand, determining a low-frequency stability diagnosable index and a high-frequency stability diagnosable index according to the three-phase low-frequency current signal and the three-phase high-frequency current signal includes:

[0024] Determining a low-frequency stability diagnosable index and a high-frequency stability diagnosable index according to the number of amplitude jumps, wherein the number of amplitude jumps is related to the peak value of each segment of the three-phase low-frequency current signal and the three-phase high-frequency current signal after being divided into J segments, where J is an integer greater than 1;

[0025] The expression of the low-frequency stationary diagnosable index is:

[0026] ;

[0027] The expression of the high-frequency stationary diagnostic index is:

[0028] ;

[0029] in, is a diagnostic indicator of low-frequency stationarity, is the number of amplitude jumps of the low-frequency current signal of phase A, is the number of amplitude jumps of the low-frequency current signal of phase B, is the number of amplitude jumps of the C-phase low-frequency current signal, is the number of amplitude jumps of the p-phase low-frequency current signal, p∈[A,B,C], For p, take the value of A, B or C The maximum value of A, B and C are the three phases of the current signal. is a diagnostic indicator of high-frequency stationarity, is the number of amplitude jumps of the high-frequency current signal of phase A, is the number of amplitude jumps of the high-frequency current signal of phase B, is the number of amplitude jumps of the C-phase high-frequency current signal, For p, take the value of A, B or C The maximum value of is the number of amplitude jumps of the p-phase high-frequency current signal, n is the amplitude jump threshold, and β is the stability parameter.

[0030] On the other hand, the process of determining the number of amplitude jumps includes:

[0031] Setting the length and step size of the sliding window, and using the sliding window to divide the three-phase high-frequency current signal and the three-phase low-frequency current signal into J segments, where J is an integer greater than 1;

[0032] Determine the peak sequence composed of the peak values ​​of each segment in the segmented current signal , p∈[A,B,C], A, B and C are the three phases of the current signal, f∈[lf,hf], lf is the low frequency, hf is the high frequency, j=1,2,…,J, j is an integer;

[0033] The number of amplitude jumps is determined according to the peak sequence, and the expression of the number of amplitude jumps is: ;

[0034] in, is the peak value of the j-th segment current signal, is the peak value of the current signal of the j+1th segment, is the minimum value between the peak value of the jth current signal and the peak value of the j+1th current signal, is the difference function value of the peak sequence, is a binary function defined as , is the stability judgment threshold.

[0035] On the other hand, if the low-frequency comprehensive diagnosable index determined according to the low-frequency energy diagnosable index and the low-frequency stability diagnosable index is not less than the low-frequency threshold, it is determined that the low-frequency fault is diagnosable, including:

[0036] Set the low frequency threshold TH lf ;

[0037] The low frequency energy diagnostic index The low-frequency stationarity can be diagnosed with the Multiply to get the comprehensive diagnosable index of three-phase low-frequency current ;

[0038] Determining whether the comprehensive diagnosable index of the three-phase low-frequency current is less than the low-frequency threshold;

[0039] If it is less than, it is determined that the low-frequency fault cannot be diagnosed;

[0040] If it is not less than, it is determined that the low-frequency fault can be diagnosed;

[0041] The low-frequency fault includes one or more combinations of broken rotor bars, misalignment and imbalance of the motor.

[0042] On the other hand, if the high-frequency comprehensive diagnosable index determined according to the high-frequency energy diagnosable index and the high-frequency stability diagnosable index is not less than the high-frequency threshold, then it is determined that the high-frequency fault is diagnosable, including:

[0043] Set the high frequency threshold TH hf ;

[0044] The high frequency energy diagnostic index The high frequency stationarity can be diagnosed with the Multiply to get the comprehensive diagnosable index of three-phase high-frequency current ;

[0045] Determining whether the comprehensive diagnosable index of the three-phase high-frequency current is less than the high-frequency threshold;

[0046] If it is less than, it is determined that the high-frequency fault cannot be diagnosed;

[0047] If it is not less than, it is determined that the high-frequency fault can be diagnosed;

[0048] The high-frequency fault includes one or more combinations of static eccentricity, dynamic eccentricity, winding looseness and inter-turn short circuit of the motor.

[0049] In order to solve the above technical problems, the present invention also provides a three-phase asynchronous motor electrical fault diagnosability evaluation system, comprising:

[0050] An acquisition unit, used for acquiring a three-phase low-frequency current signal, a three-phase high-frequency current signal and motor nameplate parameters of the three-phase asynchronous motor in a running state, wherein the frequencies of the three-phase low-frequency current signal and the three-phase high-frequency current signal are determined by a preset frequency range, and the motor nameplate parameters include rated operating parameters of the motor;

[0051] An energy diagnosable index determination unit, used to determine a low-frequency energy diagnosable index and a high-frequency energy diagnosable index according to the three-phase low-frequency current signal, the three-phase high-frequency current signal and the motor nameplate parameter, wherein the energy diagnosable index is positively correlated with the effective value of the current signal;

[0052] a stability diagnosable index determining unit, used to determine a low-frequency stability diagnosable index and a high-frequency stability diagnosable index according to the three-phase low-frequency current signal and the three-phase high-frequency current signal, wherein the stability diagnosable index is negatively correlated with the number of jumps of the current signal;

[0053] A low-frequency fault diagnosable determination unit, configured to determine that the low-frequency fault is diagnosable if the low-frequency comprehensive diagnosable index determined according to the low-frequency energy diagnosable index and the low-frequency stability diagnosable index is not less than a low-frequency threshold;

[0054] The high-frequency fault diagnosability determination unit is used to determine that the high-frequency fault is diagnosable if the high-frequency comprehensive diagnosable index determined based on the high-frequency energy diagnosable index and the high-frequency stability diagnosable index is not less than the high-frequency threshold.

[0055] In order to solve the above technical problems, the present invention also provides a three-phase asynchronous motor electrical fault diagnosability evaluation device, comprising:

[0056] Memory for storing computer programs;

[0057] A processor is used to implement the steps of the above-mentioned three-phase asynchronous motor electrical fault diagnosability assessment method when executing the computer program.

[0058] The present invention discloses a method, system and device for evaluating the diagnosability of electrical faults of three-phase asynchronous motors, which relates to the field of fault diagnosis, including: obtaining three-phase low-frequency current signals, three-phase high-frequency current signals and motor nameplate parameters under the operating state of the three-phase asynchronous motor; determining low-frequency energy diagnosable indicators, high-frequency energy diagnosable indicators, low-frequency stability diagnosable indicators and high-frequency stability diagnosable indicators; if the low-frequency comprehensive diagnosable indicators are not less than the low-frequency threshold, it is determined that the low-frequency fault is diagnosable; if the high-frequency comprehensive diagnosable indicators are not less than the high-frequency threshold, it is determined that the high-frequency fault is diagnosable. The current fluctuation caused by the fault is much smaller than that caused by the load, the energy diagnosable indicators are positively correlated with the effective value of the current signal, and the stability diagnosable indicators are negatively correlated with the number of jumps of the current signal. The higher the diagnosability, the higher the possibility that the motor electrical fault can be diagnosed, and the factors caused by the load are removed, reducing the interference of the load. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the prior art and the drawings required for use in the embodiments are 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 creative work.

[0060] Figure 1 A flow chart of a method for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor provided by the present invention;

[0061] Figure 2a A schematic diagram of a low-frequency current signal of a stator of a high-voltage three-phase asynchronous motor provided by the present invention;

[0062] Figure 2b A schematic diagram of a high-frequency current signal of a stator of a high-voltage three-phase asynchronous motor provided by the present invention;

[0063] Figure 3a A schematic diagram of the diagnosis result of a low-frequency current signal of a stator of a high-voltage three-phase asynchronous motor provided by the present invention;

[0064] Figure 3b A schematic diagram of the diagnosis result of a high-frequency current signal of a stator of a high-voltage three-phase asynchronous motor provided by the present invention;

[0065] Figure 4a A schematic diagram of a low-frequency current signal of a stator of a low-voltage three-phase asynchronous motor provided by the present invention;

[0066] Figure 4b A schematic diagram of a high-frequency current signal of a stator of a low-voltage three-phase asynchronous motor provided by the present invention;

[0067] Figure 5a A schematic diagram of the diagnosis result of a low-frequency current signal of a stator of a low-voltage three-phase asynchronous motor provided by the present invention;

[0068] Figure 5b A schematic diagram of the diagnosis result of a high-frequency current signal of a stator of a low-voltage three-phase asynchronous motor provided by the present invention;

[0069] Figure 6 A schematic diagram of the structure of a three-phase asynchronous motor electrical fault diagnosability evaluation system provided by the present invention;

[0070] Figure 7 A schematic structural diagram of a three-phase asynchronous motor electrical fault diagnosability assessment device provided by the present invention. DETAILED DESCRIPTION

[0071] The core of the present invention is to provide a method, system and device for evaluating the diagnosability of electrical faults in three-phase asynchronous motors. The higher the diagnosability, the higher the possibility that the electrical faults of the motor can be diagnosed, and the factors caused by the load are eliminated, reducing the interference of the load.

[0072] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0073] Figure 1 A flowchart of a method for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor provided by the present invention, the method for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor comprising:

[0074] S11: obtaining a three-phase low-frequency current signal, a three-phase high-frequency current signal and motor nameplate parameters of the three-phase asynchronous motor in a running state, wherein the frequencies of the three-phase low-frequency current signal and the three-phase high-frequency current signal are determined by a preset frequency range, and the motor nameplate parameters include rated operating parameters of the motor;

[0075] The working principle of electromagnetic coupling determines that it is difficult to achieve comprehensive and reliable monitoring of the motor's operating status based solely on vibration analysis. Motor fault information is often manifested in multiple physical fields such as dynamics, electromagnetism, tribology, and thermodynamics. Comprehensive use of multi-physical field response signals is an effective means to improve the accuracy of motor fault diagnosis. The motor operating status evaluation and fault diagnosis technology based on ESA (Electrical Signature Analysis) usually collects the three-phase current signal and three-phase voltage signal of the motor at the same time. The low-frequency current signal and high-frequency current signal contain the operating status information of the mechanical equipment drive, transmission, and load components, which can be used to identify equipment failure modes.

[0076] Ideally, the motor current signal is a standard 50Hz sine wave with only one peak in the spectrum. However, in actual industrial sites, the distribution of the motor's internal magnetic flux changes due to the presence of various mechanical and electrical faults. The current signal spectrum often shows many peaks, including power frequency, harmonics, sidebands, etc. These are current characteristics. Analysis of these characteristics can effectively identify motor electrical faults and some mechanical faults.

[0077] However, the motor's operating current is also affected by operating parameters, drive load, magnetic saturation, and power quality. The load driven by the motor is the main factor affecting the current. The larger the load, the greater the power the motor needs to provide, so the operating current will increase accordingly. ESA usually uses the relative change information of the current signal, which is easily affected by the operating parameters and load changes. How to eliminate missed judgments and misjudgments caused by changes in operating parameters, loads, and processes, and provide more comprehensive and reliable information support for equipment status assessment, there is currently a lack of effective quantitative evaluation methods.

[0078] Specifically, the rated operating parameters of the motor included in the motor nameplate parameters may be the rated current. The low frequency current may be set to 600-800 Hz, and the high frequency may be set to above 10000 Hz.

[0079] It should also be noted that the three-phase low-frequency current signal is a collection of the A-phase low-frequency current signal, the B-phase low-frequency current signal and the C-phase low-frequency current signal, and the three-phase high-frequency current signal is a collection of the A-phase high-frequency current signal, the B-phase high-frequency current signal and the C-phase high-frequency current signal.

[0080] S12: determining a low-frequency energy diagnosable index and a high-frequency energy diagnosable index according to the three-phase low-frequency current signal, the three-phase high-frequency current signal and the motor nameplate parameters, wherein the energy diagnosable index is positively correlated with the effective value of the current signal;

[0081] The current signal includes a three-phase high-frequency current signal and a three-phase low-frequency current signal. When determining the energy performance, the purpose is to determine the distance between the three-phase low-frequency current signal and the three-phase high-frequency current signal and the rated current. The closer to the rated current during operation, the better the energy performance.

[0082] S13: determining a low-frequency stability diagnosable index and a high-frequency stability diagnosable index according to the three-phase low-frequency current signal and the three-phase high-frequency current signal, wherein the stability diagnosable index is negatively correlated with the number of jumps of the current signal;

[0083] When determining stability, the goal is to reduce current fluctuations. The fewer the number of changes, the better the stability.

[0084] S14: If the low-frequency comprehensive diagnosable index determined according to the low-frequency energy diagnosable index and the low-frequency stability diagnosable index is not less than the low-frequency threshold, it is determined that the low-frequency fault is diagnosable;

[0085] S15: If the high-frequency comprehensive diagnosable index determined based on the high-frequency energy diagnosable index and the high-frequency stability diagnosable index is not less than the high-frequency threshold, it is determined that the high-frequency fault is diagnosable.

[0086] Since the energy diagnosable index is positively correlated with the effective value of the current signal, and the stability diagnosable index is negatively correlated with the number of jumps of the current signal, the higher the energy diagnosable index and the higher the stability diagnosable index, the larger the effective value of the current, the fewer the number of current jumps, and the current is in a relatively stable fluctuation state, which means that the fluctuation at this time is not caused by the load, so the motor fault at this time is more diagnosable.

[0087] The present invention discloses a method for evaluating the diagnosability of electrical faults of three-phase asynchronous motors, which relates to the field of fault diagnosis, including: obtaining three-phase low-frequency current signals, three-phase high-frequency current signals and motor nameplate parameters under the operating state of the three-phase asynchronous motor; determining low-frequency energy diagnosable indicators, high-frequency energy diagnosable indicators, low-frequency stability diagnosable indicators and high-frequency stability diagnosable indicators; if the low-frequency comprehensive diagnosable indicator is not less than the low-frequency threshold, it is determined that the low-frequency fault is diagnosable; if the high-frequency comprehensive diagnosable indicator is not less than the high-frequency threshold, it is determined that the high-frequency fault is diagnosable. The current fluctuation caused by the fault is much smaller than that caused by the load, the energy diagnosable indicator is positively correlated with the effective value of the current signal, and the stability diagnosable indicator is negatively correlated with the number of jumps of the current signal. The higher the diagnosability, the higher the possibility that the motor electrical fault can be diagnosed, and the factors caused by the load are removed, reducing the interference of the load.

[0088] Based on the above embodiments:

[0089] In some embodiments, determining the high-frequency energy diagnosable index and the low-frequency energy diagnosable index according to the three-phase low-frequency current signal, the three-phase high-frequency current signal and the motor nameplate parameters includes:

[0090] Determine the low-frequency energy diagnosable index and the high-frequency energy diagnosable index according to the load factor, and the load factor is positively correlated with the values ​​of the three-phase low-frequency current signal and the three-phase high-frequency current signal;

[0091] The expression of the low-frequency energy diagnostic index is:

[0092] ;

[0093] The expression of high-frequency energy diagnostic index is:

[0094] ;

[0095] in, It is a diagnostic indicator of low-frequency energy. is the load factor of the low-frequency current signal of phase A, is the load factor of the low-frequency current signal of phase B, is the load factor of the C-phase low-frequency current signal, is the load factor of the p-phase low-frequency current signal, p∈[A,B,C], For p, take the value of A, B or C The maximum value of A, B and C are the three phases of the current signal. It is a high-frequency energy diagnostic indicator. is the load factor of the high-frequency current signal of phase A, is the load factor of the high-frequency current signal of phase B, is the load factor of the C-phase high-frequency current signal, is the load factor of the p-phase high-frequency current signal, For p, take the value of A, B or C The maximum value of , m is the load factor threshold, and α is the energy parameter.

[0096] The energy diagnosable indexes of the three-phase low-frequency current signal and the three-phase high-frequency current signal are constructed respectively, and m is used for judgment. When judging the low-frequency current signal, if the maximum value of the load factor in the three phases ABC is less than m, it proves that the load capacity of the low-frequency current signal is not good and the distance from the rated current is far, so the low-frequency energy diagnosable index is set to 0. If the maximum value of the load factor in the three phases ABC is not less than m, the low-frequency energy diagnosable index is determined according to the load factor in the three-phase current, and the low-frequency energy diagnosable index is positively correlated with the load factor. Similarly, when judging the high-frequency current signal, if the maximum value of the load factor in the three phases ABC is less than m, it proves that the load capacity of the high-frequency current signal is not good and the distance from the rated current is far, so the high-frequency energy diagnosable index is set to 0. If the maximum value of the load factor in the three phases ABC is not less than m, the high-frequency energy diagnosable index is determined according to the load factor in the three-phase current, and the high-frequency energy diagnosable index is positively correlated with the load factor.

[0097] In some embodiments, the process of determining the load factor includes:

[0098] The load factor of the three-phase low-frequency current signal is determined according to the effective value of the three-phase low-frequency current signal, the effective value of the three-phase high-frequency current signal and the motor nameplate parameters. The expression of the load factor is: ;

[0099] in, is the load factor of the p-phase f-frequency current signal, is the effective value of the p-phase f-frequency current signal, f∈[lf,hf], lf is the low frequency, hf is the high frequency, rms rc It is the rated current in the motor nameplate parameters.

[0100] When p is A, the load factor is the load factor of the A-phase current signal, when p is B, the load factor is the load factor of the B-phase current signal, and when p is C, the load factor is the load factor of the C-phase current signal. When f is lf, the load factor is the load factor of the low-frequency current signal, and when f is hf, the load factor is the load factor of the high-frequency current signal. The load factor is positively correlated with the effective value of the current signal.

[0101] In some embodiments, the process of determining the effective value of the three-phase low-frequency current signal and the effective value of the three-phase high-frequency current signal includes:

[0102] According to the current effective value calculation relationship, three-phase low-frequency current signal , , And three-phase high-frequency current signal , and Determine the effective value of the three-phase low-frequency current signal separately , and And the effective value of the three-phase high-frequency current signal , and ;

[0103] Among them, the calculation formula of current effective value is: , N is the number of current signals, x i is the ith current signal.

[0104] After obtaining N current signals, obtain the sum of the squares of the current signals from the first to the Nth, then take the average of the sum of all squares, and then take the square root to get the effective value of the current. When p is A, the load factor obtained is the effective value of the current signal of phase A, when p is B, the load factor obtained is the effective value of the current signal of phase B, and when p is C, the load factor obtained is the effective value of the current signal of phase C. When f is lf, the load factor obtained is the effective value of the current of the low-frequency current signal, and when f is hf, the load factor obtained is the effective value of the current of the high-frequency current signal. The effective value of the current is positively correlated with the value of the current signal.

[0105] In some embodiments, determining a low-frequency stability diagnosable indicator and a high-frequency stability diagnosable indicator according to the three-phase low-frequency current signal and the three-phase high-frequency current signal includes:

[0106] The low-frequency stability diagnosable index and the high-frequency stability diagnosable index are determined according to the number of amplitude jumps, the number of amplitude jumps is related to the peak value of each segment of the three-phase low-frequency current signal and the three-phase high-frequency current signal after being divided into J segments, where J is an integer greater than 1;

[0107] The expression of the diagnostic index of low-frequency stationarity is:

[0108] ;

[0109] The expression of the diagnostic index of high-frequency stationarity is:

[0110] ;

[0111] in, is a diagnostic indicator of low-frequency stationarity, is the number of amplitude jumps of the low-frequency current signal of phase A, is the number of amplitude jumps of the low-frequency current signal of phase B, is the number of amplitude jumps of the C-phase low-frequency current signal, is the number of amplitude jumps of the p-phase low-frequency current signal, p∈[A,B,C], For p, take the value of A, B or C The maximum value of A, B and C are the three phases of the current signal. is a diagnostic indicator of high-frequency stationarity, is the number of amplitude jumps of the high-frequency current signal of phase A, is the number of amplitude jumps of the high-frequency current signal of phase B, is the number of amplitude jumps of the C-phase high-frequency current signal, For p, take the value of A, B or C The maximum value of is the number of amplitude jumps of the p-phase high-frequency current signal, n is the amplitude jump threshold, and β is the stability parameter.

[0112] The stability diagnosable indexes of the three-phase low-frequency current signal and the three-phase high-frequency current signal are constructed respectively, and n is used for judgment. When judging the low-frequency current signal, if the maximum value of the number of amplitude jumps in the three-phase ABC is greater than n, it proves that the stability of the low-frequency current signal is not good, so the low-frequency stability diagnosable index is set to 0. If the maximum value of the number of amplitude jumps in the three-phase ABC is not greater than n, the low-frequency stability diagnosable index is determined according to the number of amplitude jumps in the three-phase current, and the low-frequency stability diagnosable index is positively correlated with the number of amplitude jumps. Similarly, when judging the high-frequency current signal, if the maximum value of the number of amplitude jumps in the three-phase ABC is greater than n, it proves that the stability of the high-frequency current signal is not good, so the high-frequency stability diagnosable index is set to 0. If the maximum value of the number of amplitude jumps in the three-phase ABC is not greater than n, the high-frequency stability diagnosable index is determined according to the number of amplitude jumps in the three-phase current, and the high-frequency stability diagnosable index is positively correlated with the number of amplitude jumps.

[0113] In some embodiments, the process of determining the number of amplitude jumps includes:

[0114] The length and step size of the sliding window are set, and the three-phase high-frequency current signal and the three-phase low-frequency current signal are divided into J segments using the sliding window, where J is an integer greater than 1;

[0115] Determine the peak sequence composed of the peak values ​​of each segment in the segmented current signal , p∈[A,B,C], A, B and C are the three phases of the current signal, f∈[lf,hf], lf is the low frequency, hf is the high frequency, j=1,2,…,J, j is an integer;

[0116] Determine the number of amplitude jumps based on the peak sequence. The expression for the number of amplitude jumps is: ;

[0117] in, is the peak value of the j-th segment current signal, is the peak value of the current signal of the j+1th segment, is the minimum value between the peak value of the jth current signal and the peak value of the j+1th current signal, is the difference function value of the peak sequence, is a binary function defined as , is the stability judgment threshold.

[0118] The sliding window lengths are set to w for the three-phase low-frequency current signal and the three-phase high-frequency current signal. f , the sliding window step length is s f , the stability threshold is λ f , use the sliding window parameter to segment the current signal of each phase, each phase current signal contains J segments of samples, and calculate the sequence composed of the peak value of each segment of each phase current signal after segmentation , combined with the stability threshold Count the number of amplitude jumps of each phase current signal. The value of J is (signal length - sliding window length) / step length.

[0119] Using Lambda f To Make a judgment, perform binary processing on the judgment result, take 1 or 0, and finally superimpose each segment to obtain the sum of the number of amplitude jumps.

[0120] In some embodiments, if the low-frequency comprehensive diagnosable index determined according to the low-frequency energy diagnosable index and the low-frequency stability diagnosable index is not less than the low-frequency threshold, it is determined that the low-frequency fault is diagnosable, including:

[0121] Set the low frequency threshold TH lf ;

[0122] Low frequency energy can be used as a diagnostic indicator Diagnostic indicators of low-frequency stability Multiply to get the comprehensive diagnosable index of three-phase low-frequency current ;

[0123] Determine whether the comprehensive diagnosable index of the three-phase low-frequency current is less than the low-frequency threshold;

[0124] If it is less than, it is determined that the low-frequency fault cannot be diagnosed;

[0125] If it is not less than, it is determined that the low-frequency fault can be diagnosed;

[0126] The low-frequency faults include one or more combinations of broken rotor bars, misalignment and imbalance of the motor.

[0127] Corresponding thresholds are set for the comprehensive diagnosable indicators of three-phase low-frequency current and three-phase high-frequency current, and the diagnosability of the stator current signal of the three-phase asynchronous motor is determined according to the constructed diagnosable indicators and the corresponding thresholds: if the comprehensive diagnosable indicator of the three-phase low-frequency current is greater than or equal to the low-frequency threshold, low-frequency faults such as broken rotor bars, imbalance, and misalignment can be diagnosed, otherwise the above low-frequency faults cannot be diagnosed.

[0128] In some embodiments, if the high-frequency comprehensive diagnosable index determined according to the high-frequency energy diagnosable index and the high-frequency stability diagnosable index is not less than the high-frequency threshold, then it is determined that the high-frequency fault is diagnosable, including:

[0129] Set the high frequency threshold TH hf ;

[0130] High frequency energy can be used as a diagnostic indicator Diagnostic indicators of high-frequency stability Multiply to get the comprehensive diagnosable index of three-phase high-frequency current ;

[0131] Determine whether the comprehensive diagnosable index of the three-phase high-frequency current is less than the high-frequency threshold;

[0132] If it is less than, it is determined that the high-frequency fault cannot be diagnosed;

[0133] If it is not less than, it is determined that the high-frequency fault can be diagnosed;

[0134] Among them, high-frequency faults include one or more combinations of static eccentricity, dynamic eccentricity, winding looseness and inter-turn short circuit of the motor.

[0135] Corresponding thresholds are set for the comprehensive diagnosable indicators of three-phase low-frequency current and three-phase high-frequency current, and the diagnosability of the stator current signal of the three-phase asynchronous motor is determined according to the constructed diagnosability indicators and the corresponding thresholds: if the comprehensive diagnosable indicator of the three-phase high-frequency current is greater than or equal to the high-frequency threshold, high-frequency faults such as static eccentricity, dynamic eccentricity, winding looseness and turn-to-turn short circuit can be diagnosed, otherwise the above high-frequency faults cannot be diagnosed.

[0136] This application provides a specific implementation process:

[0137] The diagnosability evaluation of the stator current signal of a high-voltage three-phase asynchronous motor is carried out. The rated voltage of the motor is 6000V and the rated current is 341.4A. The parameter α is set to 0.005, the parameter β is set to 2, the low-frequency current sliding window length is 0.5s, the sliding window step is 0.25s, the high-frequency current sliding window length is 0.2s, the sliding window step is 0.1s, the stability judgment threshold is 0.2, the low-frequency current diagnosability index threshold is 0.8, and the high-frequency current diagnosability index threshold is 0.8. The low-frequency current and high-frequency current signals of the motor at 8:26:21 on April 25, 2023 are as follows: Figure 2a and Figure 2b shown. Figure 2a A schematic diagram of a low-frequency current signal of a stator of a high-voltage three-phase asynchronous motor provided by the present invention, Figure 2b The schematic diagram of the high-frequency current signal of the stator of a high-voltage three-phase asynchronous motor provided by the present invention is shown in FIG. The stator current diagnosability evaluation method of the present invention is used to evaluate the current signal. The result is as follows: Figure 3a and Figure 3b shown. Figure 3a A schematic diagram of the diagnosis result of a low-frequency current signal of a stator of a high-voltage three-phase asynchronous motor provided by the present invention; Figure 3b A schematic diagram of the diagnosis result of a high-frequency current signal of a stator of a high-voltage three-phase asynchronous motor provided by the present invention; Figure 3a and Figure 3b It can be seen that the low-frequency current energy diagnosable index, stability diagnosable index and comprehensive diagnosable index are 0.905, 0.989 and 0.895 respectively, and the high-frequency current energy diagnosable index, stability diagnosable index and comprehensive diagnosable index are 0.918, 0.989 and 0.907 respectively. The low-frequency current comprehensive diagnosable index of 0.895 is greater than the set threshold of 0.8, so low-frequency faults such as broken rotor bars, imbalance, and misalignment can be diagnosed. The high-frequency current comprehensive diagnosable index of 0.907 is greater than the set threshold of 0.8, so high-frequency faults such as static eccentricity, dynamic eccentricity, winding looseness and inter-turn short circuit can be diagnosed.

[0138] This application implements a diagnosability evaluation on the stator current signal of a low-voltage three-phase asynchronous motor. The rated voltage of the motor is 380V and the rated current is 240.7A. The parameter α is set to 0.005, the parameter β is set to 2, the low-frequency current sliding window length is 0.5s, the sliding window step is 0.25s, the high-frequency current sliding window length is 0.2s, the sliding window step is 0.1s, the stability judgment threshold is 0.2, the low-frequency current diagnosability index threshold is 0.8, and the high-frequency current diagnosability index threshold is 0.8. The low-frequency current and high-frequency current signals of the motor at 22:52:50 on October 13, 2024 are as follows: Figure 4a and Figure 4b shown. Figure 4a A schematic diagram of a low-frequency current signal of a stator of a low-voltage three-phase asynchronous motor provided by the present invention, Figure 4b A schematic diagram of a high-frequency current signal of a stator of a low-voltage three-phase asynchronous motor provided by the present invention; the group of current signals is evaluated using the stator current diagnosability evaluation method of the present invention, and the results are as follows Figure 5a and Figure 5b shown. Figure 5a A schematic diagram of the diagnosis result of a low-frequency current signal of a stator of a low-voltage three-phase asynchronous motor provided by the present invention; Figure 5bA schematic diagram of the diagnosis result of a high-frequency current signal of a stator of a low-voltage three-phase asynchronous motor provided by the present invention; Figure 5a and Figure 5b It can be seen that the low-frequency current energy diagnosable index, stability diagnosable index and comprehensive diagnosable index are 0.663, 0.393 and 0.261 respectively, and the high-frequency current energy diagnosable index, stability diagnosable index and comprehensive diagnosable index are 0.981, 0.989 and 0.970 respectively. The low-frequency current comprehensive diagnosable index of 0.261 is less than the set threshold of 0.8, so low-frequency faults such as broken rotor bars, imbalance, and misalignment are not diagnosed. The high-frequency current comprehensive diagnosable index of 0.970 is greater than the set threshold of 0.8, so high-frequency faults such as static eccentricity, dynamic eccentricity, winding looseness and inter-turn short circuit can be diagnosed.

[0139] Figure 6 A schematic diagram of a three-phase asynchronous motor electrical fault diagnosability evaluation system provided by the present invention, the three-phase asynchronous motor electrical fault diagnosability evaluation system comprising:

[0140] An acquisition unit 61 is used to acquire a three-phase low-frequency current signal, a three-phase high-frequency current signal and motor nameplate parameters of the three-phase asynchronous motor in a running state, wherein the frequencies of the three-phase low-frequency current signal and the three-phase high-frequency current signal are determined by a preset frequency range, and the motor nameplate parameters include rated operating parameters of the motor;

[0141] An energy diagnosable index determination unit 62, used to determine a low-frequency energy diagnosable index and a high-frequency energy diagnosable index according to the three-phase low-frequency current signal, the three-phase high-frequency current signal and the motor nameplate parameters, wherein the energy diagnosable index is positively correlated with the effective value of the current signal;

[0142] A stability diagnosable index determining unit 63, used to determine a low-frequency stability diagnosable index and a high-frequency stability diagnosable index according to the three-phase low-frequency current signal and the three-phase high-frequency current signal, wherein the stability diagnosable index is negatively correlated with the number of jumps of the current signal;

[0143] A low-frequency fault diagnosable determination unit 64 is used to determine that the low-frequency fault is diagnosable if the low-frequency comprehensive diagnosable index determined according to the low-frequency energy diagnosable index and the low-frequency stability diagnosable index is not less than the low-frequency threshold;

[0144] The high-frequency fault diagnosability determination unit 65 is used to determine that the high-frequency fault is diagnosable if the high-frequency comprehensive diagnosable index determined based on the high-frequency energy diagnosable index and the high-frequency stability diagnosable index is not less than the high-frequency threshold.

[0145] Based on the above embodiments:

[0146] The energy diagnosable index determining unit 62 is specifically used to determine the low-frequency energy diagnosable index and the high-frequency energy diagnosable index according to the load factor, and the load factor is positively correlated with the values ​​of the three-phase low-frequency current signal and the three-phase high-frequency current signal;

[0147] The expression of the low-frequency energy diagnostic index is:

[0148] ;

[0149] The expression of high-frequency energy diagnostic index is:

[0150] ;

[0151] in, It is a diagnostic indicator of low-frequency energy. is the load factor of the low-frequency current signal of phase A, is the load factor of the low-frequency current signal of phase B, is the load factor of the C-phase low-frequency current signal, is the load factor of the p-phase low-frequency current signal, p∈[A,B,C], For p, take the value of A, B or C The maximum value of A, B and C are the three phases of the current signal. It is a high-frequency energy diagnostic indicator. is the load factor of the high-frequency current signal of phase A, is the load factor of the high-frequency current signal of phase B, is the load factor of the C-phase high-frequency current signal, is the load factor of the p-phase high-frequency current signal, For p, take the value of A, B or C The maximum value of , m is the load factor threshold, and α is the energy parameter.

[0152] The process of determining the load factor includes:

[0153] The load factor of the three-phase low-frequency current signal is determined according to the effective value of the three-phase low-frequency current signal, the effective value of the three-phase high-frequency current signal and the motor nameplate parameters. The expression of the load factor is: ;

[0154] in, is the load factor of the p-phase f-frequency current signal, is the effective value of the p-phase f-frequency current signal, f∈[lf,hf], lf is the low frequency, hf is the high frequency, rms rc It is the rated current in the motor nameplate parameters.

[0155] The process of determining the effective value of the three-phase low-frequency current signal and the effective value of the three-phase high-frequency current signal includes:

[0156] According to the current effective value calculation relationship, three-phase low-frequency current signal , , And three-phase high-frequency current signal , and Determine the effective value of the three-phase low-frequency current signal separately , and And the effective value of the three-phase high-frequency current signal , and ;

[0157] Among them, the calculation formula of current effective value is: , N is the number of current signals, x i is the ith current signal.

[0158] The stability diagnosable index determining unit 63 is specifically used to determine the low-frequency stability diagnosable index and the high-frequency stability diagnosable index according to the number of amplitude jumps, the number of amplitude jumps is related to the peak value of each segment of the three-phase low-frequency current signal and the three-phase high-frequency current signal after being divided into J segments, and J is an integer greater than 1;

[0159] The expression of the diagnostic index of low-frequency stationarity is:

[0160] ;

[0161] The expression of the diagnostic index of high-frequency stationarity is:

[0162] ;

[0163] in, is a diagnostic indicator of low-frequency stationarity, is the number of amplitude jumps of the low-frequency current signal of phase A, is the number of amplitude jumps of the low-frequency current signal of phase B, is the number of amplitude jumps of the C-phase low-frequency current signal, is the number of amplitude jumps of the p-phase low-frequency current signal, p∈[A,B,C], For p, take the value of A, B or C The maximum value of A, B and C are the three phases of the current signal. is a diagnostic indicator of high-frequency stationarity, is the number of amplitude jumps of the high-frequency current signal of phase A, is the number of amplitude jumps of the high-frequency current signal of phase B, is the number of amplitude jumps of the C-phase high-frequency current signal, For p, take the value of A, B or C The maximum value of is the number of amplitude jumps of the p-phase high-frequency current signal, n is the amplitude jump threshold, and β is the stability parameter.

[0164] The process of determining the number of amplitude jumps includes:

[0165] The length and step size of the sliding window are set, and the three-phase high-frequency current signal and the three-phase low-frequency current signal are divided into J segments using the sliding window, where J is an integer greater than 1;

[0166] Determine the peak sequence composed of the peak values ​​of each segment in the segmented current signal , p∈[A,B,C], A, B and C are the three phases of the current signal, f∈[lf,hf], lf is the low frequency, hf is the high frequency, j=1,2,…,J, j is an integer;

[0167] Determine the number of amplitude jumps based on the peak sequence. The expression for the number of amplitude jumps is: ;

[0168] in, is the peak value of the j-th segment current signal, is the peak value of the current signal of the j+1th segment, is the minimum value between the peak value of the jth current signal and the peak value of the j+1th current signal, is the difference function value of the peak sequence, is a binary function defined as , is the stability judgment threshold.

[0169] The low frequency fault diagnosis determination unit 64 is specifically used to set the low frequency threshold TH lf ;

[0170] Low frequency energy can be used as a diagnostic indicator Diagnostic indicators of low-frequency stability Multiply to get the comprehensive diagnosable index of three-phase low-frequency current ;

[0171] Determine whether the comprehensive diagnosable index of the three-phase low-frequency current is less than the low-frequency threshold;

[0172] If it is less than, it is determined that the low-frequency fault cannot be diagnosed;

[0173] If it is not less than, it is determined that the low-frequency fault can be diagnosed;

[0174] The low-frequency faults include one or more combinations of broken rotor bars, misalignment and imbalance of the motor.

[0175] The high frequency fault diagnosis and determination unit 65 is specifically used to set the high frequency threshold TH hf ;

[0176] High frequency energy can be used as a diagnostic indicator Diagnostic indicators of high-frequency stability Multiply to get the comprehensive diagnosable index of three-phase high-frequency current ;

[0177] Determine whether the comprehensive diagnosable index of the three-phase high-frequency current is less than the high-frequency threshold;

[0178] If it is less than, it is determined that the high-frequency fault cannot be diagnosed;

[0179] If it is not less than, it is determined that the high-frequency fault can be diagnosed;

[0180] Among them, high-frequency faults include one or more combinations of static eccentricity, dynamic eccentricity, winding looseness and inter-turn short circuit of the motor.

[0181] For an introduction to the three-phase asynchronous motor electrical fault diagnosability assessment system provided in the present application, please refer to the above-mentioned embodiments, which will not be repeated here.

[0182] Figure 7 A schematic diagram of the structure of a three-phase asynchronous motor electrical fault diagnosability evaluation device provided by the present invention, the three-phase asynchronous motor electrical fault diagnosability evaluation device comprising:

[0183] A memory 71, used for storing computer programs;

[0184] The processor 72 is used to implement the steps of the above-mentioned three-phase asynchronous motor electrical fault diagnosability assessment method when executing the computer program.

[0185] For an introduction to the three-phase asynchronous motor electrical fault diagnosability assessment device provided in the present application, please refer to the above-mentioned embodiments, which will not be repeated here.

[0186] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0187] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0188] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for evaluating the diagnosability of electrical faults in a three-phase asynchronous motor, characterized in that: include: Acquire a three-phase low-frequency current signal, a three-phase high-frequency current signal and motor nameplate parameters of a three-phase asynchronous motor in a running state, wherein the frequencies of the three-phase low-frequency current signal and the three-phase high-frequency current signal are determined by a preset frequency range, and the motor nameplate parameters include rated operating parameters of the motor; Determine a low-frequency energy diagnosable index and a high-frequency energy diagnosable index according to the three-phase low-frequency current signal, the three-phase high-frequency current signal and the motor nameplate parameter, wherein the energy diagnosable index is positively correlated with the effective value of the current signal; Determining a low-frequency stability diagnosable index and a high-frequency stability diagnosable index according to the three-phase low-frequency current signal and the three-phase high-frequency current signal, wherein the stability diagnosable index is negatively correlated with the number of jumps of the current signal; If the low-frequency comprehensive diagnosable index determined according to the low-frequency energy diagnosable index and the low-frequency stability diagnosable index is not less than the low-frequency threshold, it is determined that the low-frequency fault is diagnosable; If the high-frequency comprehensive diagnosable index determined according to the high-frequency energy diagnosable index and the high-frequency stability diagnosable index is not less than the high-frequency threshold, it is determined that the high-frequency fault is diagnosable.

2. The method for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor according to claim 1, characterized in that: Determining a high-frequency energy diagnosable index and a low-frequency energy diagnosable index according to the three-phase low-frequency current signal, the three-phase high-frequency current signal and the motor nameplate parameter includes: Determining a low-frequency energy diagnosable index and a high-frequency energy diagnosable index according to a load factor, wherein the load factor is positively correlated with the values ​​of the three-phase low-frequency current signal and the three-phase high-frequency current signal; The expression of the low-frequency energy diagnosable index is: ； The expression of the high-frequency energy diagnosable index is: ； in, It is a diagnostic indicator of low-frequency energy. is the load factor of the low-frequency current signal of phase A, is the load factor of the low-frequency current signal of phase B, is the load factor of the C-phase low-frequency current signal, is the load factor of the p-phase low-frequency current signal, p∈[A,B,C], For p, take the value of A, B or C The maximum value of A, B and C are the three phases of the current signal. It is a high-frequency energy diagnostic indicator. is the load factor of the high-frequency current signal of phase A, is the load factor of the high-frequency current signal of phase B, is the load factor of the C-phase high-frequency current signal, is the load factor of the p-phase high-frequency current signal, For p, take the value of A, B or C The maximum value of , m is the load factor threshold, and α is the energy parameter.

3. The method for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor according to claim 2, characterized in that: The process of determining the load factor includes: The load factor of the three-phase low-frequency current signal is determined according to the effective value of the three-phase low-frequency current signal, the effective value of the three-phase high-frequency current signal and the motor nameplate parameters. The expression of the load factor is: ; in, is the load factor of the p-phase f-frequency current signal, is the effective value of the p-phase f-frequency current signal, f∈[lf,hf], lf is the low frequency, hf is the high frequency, rms rc It is the rated current in the motor nameplate parameters.

4. The method for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor according to claim 3, characterized in that: The process of determining the effective value of the three-phase low-frequency current signal and the effective value of the three-phase high-frequency current signal includes: According to the current effective value calculation relationship, three-phase low-frequency current signal , , And three-phase high-frequency current signal , and Determine the effective value of the three-phase low-frequency current signal separately , and And the effective value of the three-phase high-frequency current signal , and ; Among them, the current effective value calculation relationship is: , N is the number of current signals, x i is the i-th current signal, is the low-frequency current signal of phase A, is the low-frequency current signal of phase B, is the C-phase low-frequency current signal, is the high-frequency current signal of phase A, is the high-frequency current signal of phase B, is the C-phase high-frequency current signal, is the effective value of the low-frequency current signal of phase A, is the effective value of the low-frequency current signal of phase B, is the effective value of the low-frequency current signal of phase C, is the effective value of the high-frequency current signal of phase A, is the effective value of the high-frequency current signal of phase B, is the effective value of the C-phase high-frequency current signal.

5. The method for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor according to claim 1, characterized in that: Determining a low-frequency stability diagnosable index and a high-frequency stability diagnosable index according to the three-phase low-frequency current signal and the three-phase high-frequency current signal, including: Determining a low-frequency stability diagnosable index and a high-frequency stability diagnosable index according to the number of amplitude jumps, wherein the number of amplitude jumps is related to the peak value of each segment of the three-phase low-frequency current signal and the three-phase high-frequency current signal after being divided into J segments, where J is an integer greater than 1; The expression of the low-frequency stationary diagnosable index is: ； The expression of the high-frequency stationary diagnostic index is: ； in, is a diagnostic indicator of low-frequency stationarity, is the number of amplitude jumps of the low-frequency current signal of phase A, is the number of amplitude jumps of the low-frequency current signal of phase B, is the number of amplitude jumps of the C-phase low-frequency current signal, is the number of amplitude jumps of the p-phase low-frequency current signal, p∈[A,B,C], For p, take the value of A, B or C The maximum value of A, B and C are the three phases of the current signal. is a diagnostic indicator of high-frequency stationarity, is the number of amplitude jumps of the high-frequency current signal of phase A, is the number of amplitude jumps of the high-frequency current signal of phase B, is the number of amplitude jumps of the C-phase high-frequency current signal, For p, take the value of A, B or C The maximum value of is the number of amplitude jumps of the p-phase high-frequency current signal, n is the amplitude jump threshold, and β is the stability parameter.

6. The method for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor according to claim 5, characterized in that: The process of determining the number of amplitude jumps includes: Setting the length and step size of the sliding window, and using the sliding window to divide the three-phase high-frequency current signal and the three-phase low-frequency current signal into J segments, where J is an integer greater than 1; Determine the peak sequence composed of the peak values ​​of each segment in the segmented current signal , p∈[A,B,C], A, B and C are the three phases of the current signal, f∈[lf,hf], lf is the low frequency, hf is the high frequency, j=1,2,…,J, j is an integer; The number of amplitude jumps is determined according to the peak sequence, and the expression of the number of amplitude jumps is: ； in, is the peak value of the j-th segment current signal, is the peak value of the current signal of the j+1th segment, is the minimum value between the peak value of the jth current signal and the peak value of the j+1th current signal, is the difference function value of the peak sequence, is a binary function defined as , is the stability judgment threshold.

7. The method for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor according to any one of claims 1 to 6, characterized in that: If the low-frequency comprehensive diagnosable index determined according to the low-frequency energy diagnosable index and the low-frequency stability diagnosable index is not less than the low-frequency threshold, then it is determined that the low-frequency fault is diagnosable, including: Set the low frequency threshold TH lf ; The low frequency energy diagnostic index The low-frequency stationarity can be diagnosed with the Multiply to get the comprehensive diagnosable index of three-phase low-frequency current ; Determining whether the comprehensive diagnosable index of the three-phase low-frequency current is less than the low-frequency threshold; If it is less than, it is determined that the low-frequency fault cannot be diagnosed; If it is not less than, it is determined that the low-frequency fault can be diagnosed; The low-frequency fault includes one or more combinations of broken rotor bars, misalignment and imbalance of the motor.

8. The method for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor according to any one of claims 1 to 6, characterized in that: If the high-frequency comprehensive diagnosable index determined according to the high-frequency energy diagnosable index and the high-frequency stability diagnosable index is not less than the high-frequency threshold, then it is determined that the high-frequency fault is diagnosable, including: Set the high frequency threshold TH hf ; The high frequency energy diagnostic index The high frequency stationarity can be diagnosed with the Multiply to get the comprehensive diagnosable index of three-phase high-frequency current ; Determining whether the comprehensive diagnosable index of the three-phase high-frequency current is less than the high-frequency threshold; If it is less than, it is determined that the high-frequency fault cannot be diagnosed; If it is not less than, it is determined that the high-frequency fault can be diagnosed; The high-frequency fault includes one or more combinations of static eccentricity, dynamic eccentricity, winding looseness and inter-turn short circuit of the motor.

9. A three-phase asynchronous motor electrical fault diagnosability assessment system, characterized in that: include: An acquisition unit, used for acquiring a three-phase low-frequency current signal, a three-phase high-frequency current signal and motor nameplate parameters of the three-phase asynchronous motor in a running state, wherein the frequencies of the three-phase low-frequency current signal and the three-phase high-frequency current signal are determined by a preset frequency range, and the motor nameplate parameters include rated operating parameters of the motor; An energy diagnosable index determination unit, used to determine a low-frequency energy diagnosable index and a high-frequency energy diagnosable index according to the three-phase low-frequency current signal, the three-phase high-frequency current signal and the motor nameplate parameter, wherein the energy diagnosable index is positively correlated with the effective value of the current signal; a stability diagnosable index determining unit, used to determine a low-frequency stability diagnosable index and a high-frequency stability diagnosable index according to the three-phase low-frequency current signal and the three-phase high-frequency current signal, wherein the stability diagnosable index is negatively correlated with the number of jumps of the current signal; A low-frequency fault diagnosable determination unit, configured to determine that the low-frequency fault is diagnosable if the low-frequency comprehensive diagnosable index determined according to the low-frequency energy diagnosable index and the low-frequency stability diagnosable index is not less than a low-frequency threshold; The high-frequency fault diagnosability determination unit is used to determine that the high-frequency fault is diagnosable if the high-frequency comprehensive diagnosable index determined based on the high-frequency energy diagnosable index and the high-frequency stability diagnosable index is not less than the high-frequency threshold.

10. A three-phase asynchronous motor electrical fault diagnosability assessment device, characterized in that: include: Memory for storing computer programs; A processor is used to implement the steps of the method for evaluating the diagnosability of electrical faults of a three-phase asynchronous motor as claimed in any one of claims 1 to 8 when executing the computer program.

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