Generator stator core loss experiment method and system

Abstract

The invention relates to the technical field of generator stator core loss experiments, in particular to a generator stator core loss experiment method and system, and aims to realize detection of surface loss and deep loss of a stator core, improve comprehensiveness of loss detection of the stator core, reduce excitation current, reduce reactive loss and improve reliability of the stator core loss detection by stacking high-frequency current and high-frequency current. The safety and reliability of experimental operation are improved, the operation difficulty is reduced, the sensitivity of defect detection is enhanced through differentiated eddy current distribution, and the actual experimental requirements are met.

Description

Technical Field

[0001] The present invention relates to the technical field of generator stator core loss experiments, and specifically relates to a method and system for generator stator core loss experiments. Background Art

[0002] The iron core on the stator is an important part of the generator. The iron core defect detection test can detect the fault points of the iron core earlier and avoid the expansion of faults. In traditional stator core tests, multiple turns of excitation coils are usually wound around the stator core, and a power frequency excitation current is passed through the excitation coils to generate a magnetic field in the stator core, and then eddy currents are generated to heat the iron core. The excitation voltage generally selects a 380V power frequency power supply, and the excitation current varies according to the number of winding turns. Generally speaking, the larger the generator capacity, the larger the required excitation current.

[0003] For example, the Chinese utility model patent with the application number 201620582244.X provides a large generator stator core loss detection device that uses power frequency large current excitation for loss detection. Although the power supply capacity is reduced, there are still the following problems: Large excitation current: For large-capacity units, large cross-section coils need to be wound, and the on-site test operation is complex and the safety is low.

[0004] Low energy efficiency: The low power factor of power frequency large current excitation leads to large reactive power loss and high energy consumption in the system.

[0005] Moreover, using power frequency excitation can only detect the internal defects of the stator core and cannot fully detect the stator core loss. Therefore, the existing generator stator core loss experimental methods cannot meet the actual needs. Summary of the Invention

[0006] The purpose of the present invention is to provide a method and system for generator stator core loss experiments to solve the technical problems of large current and high energy consumption in current generator stator core loss experiments.

[0007] The solution of the present invention to the above technical problems: A generator stator core loss experimental system includes: An excitation unit, which is used to perform power frequency excitation and high frequency excitation on the stator core; A temperature detection unit, which is used to obtain the temperature H at different positions of the stator core; A temperature processing unit, which is used to obtain the temperature rise rate at the corresponding position of the stator core and the temperature difference per unit time according to the temperatures at different positions of the stator core; A fault judgment unit, which is used to judge the loss state at the corresponding position of the stator core according to the temperature rise rate at the corresponding position of the iron core and the temperature difference per unit time.

[0008] Further defined, the exciting action unit includes: A multi-frequency excitation signal transmitting module, configured to generate a corresponding multi-frequency excitation signal according to the power frequency and the high frequency; An exciting action module, configured to perform power frequency excitation and high frequency excitation of corresponding frequencies on the stator core according to the multi-frequency excitation signal.

[0009] Further defined, the multi-frequency excitation signal Specifically:

[0010] Wherein, I 工 is the amplitude of the power frequency excitation current, f 工 is the frequency of the power frequency excitation current, I 高 is the amplitude of the high frequency excitation current, f 高 is the frequency of the high frequency excitation current, is the difference between the phase of the high frequency excitation current and the phase of the power frequency excitation current, and t is time.

[0011] Further defined, the exciting action unit further includes: A magnetic flux density detection module, configured to detect the magnetic flux density at different positions of the stator core; configured to judge whether it exceeds the peak threshold according to the magnetic flux density at different positions of the core. If so, send an exciting signal adjustment signal; if not, be silent; A multi-frequency excitation signal adjustment module, configured to reduce the amplitude I of the high frequency excitation current 高 or increase the difference between the phase of the high frequency excitation current and the phase of the power frequency excitation current .

[0012] Further defined, the frequency f of the high frequency excitation current 高 and the frequency f of the power frequency excitation current 工 Satisfy: f 高 =nf 工 Wherein, n is a positive integer.

[0013] Further defined, the temperature processing unit includes: A temperature rise rate calculation module, configured to calculate the temperature rise rate V of the corresponding position of the stator core according to the temperature H at different positions of the stator core and the temperature rise time m; A temperature difference calculation module, configured to calculate the temperature difference S per unit time at different positions of the stator core according to the temperature H at different positions of the stator core and the temperature rise time m; A temperature threshold judgment module, configured to judge whether the temperature H at different positions of the core exceeds the temperature rise threshold k according to the set temperature rise threshold M; A timing module for recording the temperature rise time m.

[0014] Further defined, the fault judgment unit includes: A surface short - circuit judgment module for judging whether there is a short - circuit on the surface of the stator core according to the temperature rise rate V at the corresponding position of the stator core. If the temperature rise rate V > 3K / min, there is a short - circuit on the surface of the stator core; if not, there is no loss on the surface of the stator core. A deep - layer deterioration judgment module for judging whether there is deterioration in the deep layer of the stator core according to the temperature rise rate V at the corresponding position of the stator core and the temperature difference S per unit time at different positions of the stator core. If the temperature rise rate V = (1 - 2)K / min and the temperature difference S per unit time > 10K / 15min, there is deterioration in the deep layer of the stator core; if not, there is no deterioration in the deep layer of the stator core. A fault point judgment module for judging whether there is a fault in the deep layer of the stator core according to the temperature H at different positions of the stator core, the temperature rise threshold M, and the temperature rise time m at the corresponding position. If the temperature H of the stator core is greater than the temperature rise threshold M and the temperature rise time m exceeding the temperature rise threshold M > 10min, there is a fault point in the stator core; if not, there is no fault point in the stator core.

[0015] A method for testing the loss of a generator stator core includes the following steps: Apply power - frequency excitation and high - frequency excitation to the stator core. Obtain the temperature H at different positions of the stator core. Obtain the temperature rise rate and the temperature difference per unit time at the corresponding position of the stator core according to the temperature at different positions of the stator core. Judge the loss state at the corresponding position of the stator core according to the temperature rise rate and the temperature difference per unit time at the corresponding position of the iron core.

[0016] Further defined, the step of applying power - frequency excitation and high - frequency excitation to the stator core is specifically: Generate corresponding multi - frequency excitation signals according to the power - frequency and high - frequency frequencies. Apply power - frequency excitation and high - frequency excitation at the corresponding frequencies to the stator core according to the multi - frequency excitation signals. After receiving the excitation signal adjustment signal, reduce the amplitude I of the high - frequency excitation current 高 Or increase the difference between the phase of the high - frequency excitation current and the phase of the power - frequency excitation current ; Detect the magnetic flux density at different positions of the stator core; used to judge whether it exceeds the peak threshold according to the magnetic flux density at different positions of the iron core. If so, send an excitation signal adjustment signal; if not, be silent. The multi - frequency excitation signal is specifically:

[0017] Among them, I 工 is the amplitude of the power frequency excitation current, f 工 is the frequency of the power frequency excitation current, I 高 is the amplitude of the high-frequency excitation current, f 高 is the frequency of the high-frequency excitation current, is the difference between the phase of the high-frequency excitation current and the phase of the power frequency excitation current, and t is time; The frequency f 高 of the high-frequency excitation current and the frequency f 工 of the power frequency excitation current satisfy: f 高 =nf 工 where n is a positive integer.

[0018] Further limited, the step of obtaining the temperature rise rate and the temperature difference per unit time at the corresponding position of the stator core according to the temperature at different positions of the stator core is specifically as follows: Record the temperature rise time m; Calculate the temperature rise rate V at the corresponding position of the stator core according to the temperature H at different positions of the stator core and the temperature rise time m; Calculate the temperature difference S per unit time at different positions of the stator core according to the temperature H at different positions of the stator core and the temperature rise time m; According to the set temperature rise threshold M, judge whether the temperature H at different positions of the iron core exceeds the temperature rise threshold k; The step of judging the loss state at the corresponding position of the stator core according to the temperature rise rate and the temperature difference per unit time at the corresponding position of the iron core is specifically as follows: Judge whether there is a short circuit on the surface of the stator core according to the temperature rise rate V at the corresponding position of the stator core. If the temperature rise rate V>3K / min, there is a short circuit on the surface of the stator core; if not, there is no loss on the surface of the stator core; Judge whether there is deterioration in the deep layer of the stator core according to the temperature rise rate V at the corresponding position of the stator core and the temperature difference S per unit time at different positions of the stator core. If the temperature rise rate V=(1~2)K / min and the temperature difference S per unit time>10K / 15min, there is deterioration in the deep layer of the stator core; if not, there is no deterioration in the deep layer of the stator core; Judge whether there is a fault in the deep layer of the stator core according to the temperature H at different positions of the stator core, the temperature rise threshold M and the temperature rise time m at the corresponding position. If the temperature H of the stator core is greater than the temperature rise threshold M and the temperature rise time exceeding the temperature rise threshold M>10min, there is a fault point in the stator core; if not, there is no fault point in the stator core.

[0019] The beneficial effects of the present invention are as follows: By superimposing power frequency current and high-frequency current, the present invention realizes the detection of the surface and deep layer losses of the stator core, improves the comprehensiveness of the stator core loss detection, reduces the excitation current at the same time, reduces the reactive power loss, improves the safety and reliability of the experimental operation, reduces the operation difficulty, and enhances the sensitivity of defect detection through the differential eddy current distribution, meeting the actual experimental requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the experimental system for the stator core loss of the generator of the present invention; Figure 2 It is a schematic diagram of the principle of the experimental system for the stator core loss of the motor of the present invention; Figure 3 It is a flowchart of the experimental method for the stator core loss of the generator of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] Embodiment 1 Referring to Figure 1 and Figure 2 , the present invention provides an experimental system for the stator core loss of a generator, including: An excitation unit for applying power frequency excitation and high-frequency excitation to the stator core; A temperature detection unit for obtaining the temperature H at different positions of the stator core; A temperature processing unit for obtaining the temperature rise rate and the temperature difference per unit time at the corresponding positions of the stator core according to the temperatures at different positions of the stator core; A fault judgment unit for judging the loss state at the corresponding positions of the stator core according to the temperature rise rate and the temperature difference per unit time at the corresponding positions of the core.

[0023] Further explanation, the excitation unit includes: A multi-frequency excitation signal sending module for generating corresponding multi-frequency excitation signals according to the power frequency and the high-frequency; Among them, the multi-frequency excitation signal Specifically:

[0024] Among them, I 工 is the amplitude of the power frequency excitation current, f 工 is the frequency of the power frequency excitation current, I高 is the amplitude of the high-frequency excitation current, f 高 is the frequency of the high-frequency excitation current, is the difference between the phase of the high-frequency excitation current and the phase of the power-frequency excitation current, that is = phase of high-frequency excitation current - phase of power-frequency excitation current, and t is time.

[0025] Specifically, the difference between the phase of the high-frequency excitation current and the phase of the power-frequency excitation current calculates the magnetic field superposition effect at different phase differences through the finite element simulation analysis method, and judges whether the peak value of the magnetic flux density corresponding to different phase differences (0° to 180°) is less than 1.4T. If so, the corresponding phase difference is collected; if not, the corresponding phase difference is discarded, so as to obtain a phase difference data set that meets the magnetic flux density.

[0026] Specifically, the frequency f of the high-frequency excitation current 高 and the frequency f of the power-frequency excitation current 工 satisfy: f 高 = nf 工 Usually, the frequency f of the high-frequency excitation current 高 = 300Hz to 1000Hz; where n is a positive integer, used to avoid non-harmonic interference.

[0027] The excitation function module is used to perform power-frequency excitation and high-frequency excitation of corresponding frequencies on the stator core according to the multi-frequency excitation signal.

[0028] By superimposing the power-frequency and high-frequency currents, taking a 100MW hydro-generator unit as an example, if a magnetic flux of 1.2T is to be established, a single power-frequency excitation current usually requires 550A to 600A. When using the superimposed excitation current of power-frequency and high-frequency (taking 300Hz as an example), both the power-frequency current and the high-frequency current only need about 150A, reducing the current magnitude.

[0029] Further explanation, the excitation function unit further includes: The magnetic flux density detection module is used to detect the magnetic flux density at different positions of the stator core; it is used to judge whether it exceeds the peak threshold according to the magnetic flux density at different positions of the iron core. If so, an excitation signal adjustment signal is sent; if not, it remains silent; Specifically, multiple Hall sensors can be selected to be arranged on the surface of the stator core to detect the magnetic flux density at the corresponding positions of the stator core in real time. The peak threshold is 1.4T, so it is necessary to judge whether the magnetic flux density at the corresponding position of the stator core exceeds 1.4T.

[0030] The multi-frequency excitation signal adjustment module is used to reduce the amplitude I of the high-frequency excitation current after receiving the excitation signal adjustment signal 高Or increase the difference between the phase of the high-frequency excitation current and the phase of the power-frequency excitation current .

[0031] Specifically, when adjusting the multi-frequency excitation signal, if adjusting the difference between the phase of the high-frequency excitation current and the phase of the power-frequency excitation current , where The value range of is the phase difference data set.

[0032] Further explanation, the temperature processing unit includes: Specifically, the temperature detection module can be selected as an infrared thermal imager, which scans the surface of the stator core once at an interval of a set time to obtain the temperature H corresponding to the surface of the stator core; the interval of the set time can be selected as 5 min.

[0033] The temperature rise rate calculation module is used to calculate the temperature rise rate V of the corresponding position of the stator core according to the temperature H at different positions of the stator core and the temperature rise time m; Specifically, since the surface temperature H of the stator core is collected once every 5 min, the temperature rise time m is an integer multiple of 5 min, and the temperature rise rate V is the ratio of the temperature collected by the infrared thermal imager twice adjacent to each other to the interval time.

[0034] The temperature difference calculation module is used to calculate the temperature difference S per unit time at different positions of the stator core according to the temperature H at different positions of the stator core and the temperature rise time m; The temperature threshold judgment module is used to judge whether the temperature H at different positions of the iron core exceeds the temperature rise threshold k according to the set temperature rise threshold M; The timing module is used to record the temperature rise time m.

[0035] Further explanation, the fault judgment unit includes: The surface short-circuit judgment module is used to judge whether there is a short circuit on the surface of the stator core according to the temperature rise rate V of the corresponding position of the stator core. If the temperature rise rate V>3 K / min, there is a short circuit on the surface of the stator core; if not, there is no loss on the surface of the stator core; The deep deterioration judgment module is used to judge whether there is deep deterioration of the stator core according to the temperature rise rate V of the corresponding position of the stator core and the temperature difference S per unit time at different positions of the stator core; if the temperature rise rate V=(1~2) K / min, and the temperature difference S per unit time>10 K / 15 min, there is deep deterioration of the stator core; if not, there is no deep deterioration of the stator core; The fault point judgment module is used to judge whether there is a fault in the deep layer of the stator core according to the temperature H at different positions of the stator core, the temperature rise threshold M and the temperature rise time m at the corresponding position; if the temperature H of the stator core is greater than the temperature rise threshold M, and the temperature rise time exceeding the temperature rise threshold M>10 min, there is a fault point in the stator core; if not, there is no fault point in the stator core.

[0036] Example 2 Reference Figure 3 , this embodiment provides a method for testing the core loss of a generator stator, including the following steps: Apply power frequency excitation and high-frequency excitation to the stator core; Obtain the temperatures at different positions of the stator core; Obtain the temperature rise rate and the temperature difference per unit time at the corresponding positions of the stator core based on the temperatures at different positions of the stator core; Judge the loss state at the corresponding positions of the stator core according to the temperature rise rate and the temperature difference per unit time at the corresponding positions of the core.

[0037] Further explanation, the steps of applying power frequency excitation and high-frequency excitation to the stator core are specifically as follows: Generate corresponding multi-frequency excitation signals according to the power frequency and high-frequency frequencies; Apply power frequency excitation and high-frequency excitation at the corresponding frequencies to the stator core according to the multi-frequency excitation signals; After receiving the excitation signal adjustment signal, reduce the amplitude I of the high-frequency excitation current 高 or increase the phase difference between the high-frequency excitation current phase and the power frequency excitation current phase ; Detect the magnetic flux density at different positions of the stator core; used to judge whether it exceeds the peak threshold according to the magnetic flux density at different positions of the core. If so, send an excitation signal adjustment signal; if not, be silent; Further explanation, the multi-frequency excitation signal is specifically:

[0038] Among them, I 工 is the amplitude of the power frequency excitation current, f 工 is the frequency of the power frequency excitation current, I 高 is the amplitude of the high-frequency excitation current, f 高 is the frequency of the high-frequency excitation current, is the phase difference between the high-frequency excitation current phase and the power frequency excitation current phase, and t is time; Further explanation, the frequency f of the high-frequency excitation current 高 and the frequency f of the power frequency excitation current 工 satisfy: f 高 =nf 工 where n is a positive integer.

[0039] Further explanation, the steps of obtaining the temperature rise rate and the temperature difference per unit time at the corresponding positions of the stator core based on the temperatures at different positions of the stator core are specifically as follows: Record the temperature rise time m; Calculate the temperature rise rate V of the corresponding position of the stator core according to the temperature H and the temperature rise time m at different positions of the stator core; Calculate the temperature difference S per unit time at different positions of the stator core according to the temperature H and the temperature rise time m at different positions of the stator core; According to the set temperature rise threshold M, determine whether the temperature H at different positions of the iron core exceeds the temperature rise threshold k.

[0040] Further explanation, the steps of judging the loss state of the corresponding position of the stator core according to the temperature rise rate and the temperature difference per unit time of the corresponding position of the iron core are specifically as follows: Judge whether there is a short circuit on the surface of the stator core according to the temperature rise rate V of the corresponding position of the stator core. If the temperature rise rate V > 3K / min, there is a short circuit on the surface of the stator core; if not, there is no loss on the surface of the stator core; Judge whether there is deterioration in the deep layer of the stator core according to the temperature rise rate V of the corresponding position of the stator core and the temperature difference S per unit time at different positions of the stator core; if the temperature rise rate V = (1 - 2)K / min, and the temperature difference S per unit time > 10K / 15min, there is deterioration in the deep layer of the stator core; if not, there is no deterioration in the deep layer of the stator core; Judge whether there is a fault in the deep layer of the stator core according to the temperature H at different positions of the stator core, the temperature rise threshold M and the temperature rise time m of the corresponding position; if the temperature H of the stator core is greater than the temperature rise threshold M, and the temperature rise time exceeding the temperature rise threshold M > 10min, there is a fault point in the stator core; if not, there is no fault point in the stator core.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the present invention; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present invention.

Claims

1. A generator stator core loss test system, characterized in that: include: An excitation unit, used for power frequency excitation and high frequency excitation of the stator core; A temperature detection unit, used to obtain the temperature H at different positions of the stator core; A temperature processing unit, used to obtain the temperature rise rate of the corresponding position of the stator core and the temperature difference per unit time according to the temperature of different positions of the stator core; The fault judgment unit is used to judge the loss state of the corresponding position of the stator core according to the temperature rise rate of the corresponding position of the core and the temperature difference per unit time.

2. The generator stator core loss test system according to claim 1, characterized in that: The excitation unit comprises: A multi-frequency excitation signal sending module is used to generate corresponding multi-frequency excitation signals according to the power frequency and the high frequency; The excitation module is used to perform industrial frequency excitation and high frequency excitation of the stator core at corresponding frequencies according to the multi-frequency excitation signal.

3. The generator stator core loss test system according to claim 2, characterized in that: The multi-frequency excitation signal Specifically: Among them, I 工 is the amplitude of the power frequency excitation current, f 工 is the frequency of the power frequency excitation current, I 高 is the amplitude of the high frequency excitation current, f 高 is the frequency of the high-frequency excitation current, is the difference between the high-frequency excitation current phase and the power frequency excitation current phase, and t is the time.

4. The generator stator core loss test system according to claim 3, characterized in that: The excitation action unit also includes: The magnetic flux density detection module is used to detect the magnetic flux density at different positions of the stator core; it is used to determine whether the magnetic flux density at different positions of the core exceeds the peak threshold value, and if so, send an excitation signal adjustment signal; if not, keep silent; The multi-frequency excitation signal adjustment module is used to reduce the amplitude I of the high-frequency excitation current after receiving the excitation signal adjustment signal. 高 Or increase the difference between the high frequency excitation current phase and the power frequency excitation current phase .

5. The generator stator core loss test system according to claim 3 or 4, characterized in that: The frequency f of the high-frequency excitation current 高 The frequency f of the power frequency excitation current 工 satisfy: f 高 =nf 工 Wherein, n is a positive integer.

6. The generator stator core loss test system according to claim 5, characterized in that: The temperature processing unit comprises: A temperature rise rate calculation module is used to calculate the temperature rise rate V at the corresponding position of the stator core according to the temperature H at different positions of the stator core and the temperature rise time m; A temperature difference calculation module, used to calculate the temperature difference S per unit time at different positions of the stator core according to the temperature H at different positions of the stator core and the temperature rise time m; The temperature threshold judgment module is used to judge whether the temperature H at different positions of the core exceeds the temperature rise threshold k according to the set temperature rise threshold M; Timing module, used to record the temperature rise time m.

7. The generator stator core loss test system according to claim 6, characterized in that: The fault judgment unit comprises: The surface short circuit judgment module is used to judge whether there is a short circuit on the surface of the stator core according to the temperature rise rate V at the corresponding position of the stator core. If the temperature rise rate V>3K / min, there is a short circuit on the surface of the stator core; if not, there is no loss on the surface of the stator core; The deep layer degradation judgment module is used to judge whether there is degradation in the deep layer of the stator core according to the temperature rise rate V at the corresponding position of the stator core and the temperature difference S at different positions of the stator core per unit time; if the temperature rise rate V=(1~2)K / min, and the temperature difference S per unit time>10K / 15min, then there is degradation in the deep layer of the stator core; if not, there is no degradation in the deep layer of the stator core; The fault point judgment module is used to judge whether there is a fault in the deep layer of the stator core according to the temperature H at different positions of the stator core, the temperature rise threshold M and the temperature rise time m at the corresponding position; if the temperature H of the stator core is greater than the temperature rise threshold M, and the temperature rise time m exceeding the temperature rise threshold M is greater than 10min, then there is a fault point in the stator core; if not, there is no fault point in the stator core.

8. A generator stator core loss test method, characterized in that: The following steps are involved: Performing power frequency excitation and high frequency excitation on the stator core; Obtain the temperature H at different positions of the stator core; According to the temperature at different positions of the stator core, the temperature rise rate at the corresponding position of the stator core and the temperature difference per unit time are obtained; The loss state of the corresponding position of the stator core is determined based on the temperature rise rate of the corresponding position of the core and the temperature difference per unit time.

9. The generator stator core loss test method according to claim 8, characterized in that: The steps of performing power frequency excitation and high frequency excitation on the stator core are specifically as follows: Generate corresponding multi-frequency excitation signals according to the power frequency and the high-frequency frequency; According to the multi-frequency excitation signal, the stator core is excited by the power frequency and high frequency of the corresponding frequency; After receiving the excitation signal adjustment signal, reduce the amplitude of the high-frequency excitation current I 高 Or increase the difference between the high frequency excitation current phase and the power frequency excitation current phase ; Detect the magnetic flux density at different positions of the stator core; use it to determine whether the magnetic flux density at different positions of the core exceeds the peak threshold, if so, send an excitation signal adjustment signal; if not, keep silent; The multi-frequency excitation signal is specifically: Among them, I 工 is the amplitude of the power frequency excitation current, f 工 is the frequency of the power frequency excitation current, I 高 is the amplitude of the high frequency excitation current, f 高 is the frequency of the high-frequency excitation current, is the difference between the high-frequency excitation current phase and the power frequency excitation current phase, and t is the time; The frequency f of the high-frequency excitation current 高 The frequency f of the power frequency excitation current 工 satisfy: f 高 =nf 工 Wherein, n is a positive integer.

10. The generator stator core loss test method according to claim 9, characterized in that: The step of obtaining the temperature rise rate and the temperature difference per unit time at the corresponding position of the stator core according to the temperature at different positions of the stator core is specifically as follows: Record the temperature rise time in m; The temperature rise rate V at the corresponding position of the stator core is calculated according to the temperature H at different positions of the stator core and the temperature rise time m; Calculate the temperature difference S per unit time at different positions of the stator core according to the temperature H at different positions of the stator core and the temperature rise time m; According to the set temperature rise threshold M, determine whether the temperature H at different positions of the core exceeds the temperature rise threshold k; The step of judging the loss state of the corresponding position of the stator core according to the temperature rise rate of the corresponding position of the core and the temperature difference per unit time is specifically as follows: According to the temperature rise rate V at the corresponding position of the stator core, it is judged whether there is a short circuit on the surface of the stator core. If the temperature rise rate V>3K / min, there is a short circuit on the surface of the stator core; if not, there is no loss on the surface of the stator core; According to the temperature rise rate V at the corresponding position of the stator core and the temperature difference S at different positions of the stator core per unit time, it is judged whether there is degradation in the deep layer of the stator core; if the temperature rise rate V = (1~2) K / min, and the temperature difference S per unit time> 10K / 15min, then there is degradation in the deep layer of the stator core; if not, there is no degradation in the deep layer of the stator core; According to the temperature H, temperature rise threshold M and temperature rise time m at different positions of the stator core, determine whether there is a fault in the deep layer of the stator core; if the temperature H of the stator core is greater than the temperature rise threshold M, and the temperature rise time exceeding the temperature rise threshold M is greater than 10 minutes, there is a fault point in the stator core; If not, there is no fault point in the stator core.

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