Method and system for evaluating insulation latent fault of power distribution equipment

Abstract

The invention relates to the technical field of power distribution equipment, and particularly discloses a power distribution equipment insulation latent fault assessment method and system.The insulation resistance value of an external insulator material of the power distribution equipment is measured through a megohmmeter, and the absorption ratio of the insulator material is obtained through calculation; obtaining an insulation abnormal signal of the power distribution equipment; performing discharge detection on a discharge detection area on the surface of the power distribution equipment, and calculating to obtain a discharge coefficient ratio of the discharge detection area; obtaining a region abnormal signal, and calculating to obtain a discharge capacity risk fluctuation expression extreme value of the discharge detection region i; a discharge early warning signal is obtained, temperature detection is carried out on a discharge detection area through an infrared thermal imaging sensor, a thermal abnormal signal or a thermal stable signal is obtained, and fault assessment is carried out in the aspects of the insulation state, the discharge capacity, the operating temperature and the like of an external insulation material of the power distribution equipment so as to find and solve insulation faults of the power distribution equipment in advance. And stable and normal operation of equipment is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution equipment, and in particular to a method and system for evaluating latent insulation faults of power distribution equipment. Background Art

[0002] At present, insulation damage failures often occur in common distribution network equipment in open-air environments. At the same time, a large number of equipment have latent insulation hazards and failures. The insulation detection method for distribution network distribution line equipment failures is mostly discharge detection; During the detection process, on the one hand, the detection personnel make judgments and evaluations based on the manual detection results, without accurate evaluation criteria, and are subject to many subjective influences; on the other hand, the general partial discharge test is measured under conditions higher than the normal operating voltage of the equipment. If the normal operating voltage is reached, latent faults are difficult to detect. At this time, manual detection may bring certain safety hazards and inaccurate measurement results. Summary of the invention

[0003] The purpose of the present invention is to provide a method and system for evaluating latent insulation faults of power distribution equipment to solve the above-mentioned problems.

[0004] The purpose of the present invention can be achieved by the following technical solutions: A method for evaluating latent insulation faults of power distribution equipment, comprising: The insulation resistance value of the external insulation material of the power distribution equipment is measured by using a megohmmeter, and the absorption ratio JK of the insulation material is calculated based on the measured insulation resistance value; and compared with the absorption ratio threshold JKyz; an insulation stability signal of the power distribution equipment or an insulation abnormality signal of the power distribution equipment is obtained; Based on the insulation abnormality signal of the distribution equipment, the surface of the distribution equipment is divided into several discharge detection areas, and the discharge detection areas are marked as i, where i is 1, 2, 3...; discharge detection is performed on the discharge detection areas on the surface of the distribution equipment, and the discharge coefficient ratio FIB of the discharge detection area is calculated. i ; and compare with the preset discharge coefficient ratio FIBin; obtain regional stability signal or regional abnormal signal; Based on the regional abnormal signal, obtain the regional current change curve Q of the surface discharge detection area of ​​the distribution equipment （i） ; pass Calculate the discharge amount GDF of the discharge detection area i i ; Then through Calculate and obtain the discharge amount risk fluctuation extreme value QI of the discharge detection area i i ; Then the discharge risk fluctuation performance extreme value QI iCompare with the discharge amount safety value Qan; obtain a discharge risk signal or a discharge warning signal; Based on the discharge warning signal, the temperature of the discharge detection area i is detected by an infrared thermal imaging sensor to obtain the temperature distribution image of the discharge detection area i; the temperature heterogeneity ratio SB in the discharge detection area i is calculated. i ; Then compare it with the temperature heterogeneity ratio extreme value SBJ; obtain thermal anomaly signal or thermal stability signal.

[0005] As a further solution of the present invention: the calculation process of the absorption ratio JK is: A11: Connect a DC voltage with a voltage value of KU to the insulation material of the power distribution equipment, and then use a megohmmeter to perform periodic insulation resistance testing on the power distribution equipment; A12: Get the detection current value at each detection time point n within the insulation resistance detection cycle T and mark it as JI n ; A13: Pass Calculate and obtain the insulation resistance value JR of the power distribution equipment at each detection time point n n ; A14: Obtain the insulation resistance values ​​at the initial state time point ct and the final state time point wt within the insulation resistance detection period T, and mark them as initial state resistance values ​​JR ct and final resistance JR wt ; pass Calculate the absorption ratio JK of the insulating material.

[0006] As a further solution of the present invention: the process of the periodic insulation resistance detection is to take the external DC voltage of the distribution equipment as the starting time 0, the unit time t as the detection time interval, and divide the insulation resistance detection period RT into several detection time points, which are marked as n respectively, where n is 1, 2, 3...

[0007] As a further solution of the present invention: the absorption ratio JK of the insulation material of the power distribution equipment is compared with the absorption ratio threshold JKyz: If the absorption ratio JK of the insulation material of the power distribution equipment is greater than or equal to the absorption ratio threshold JKyz, a power distribution equipment insulation stability signal is generated; If the absorption ratio JK of the insulation material of the power distribution equipment is less than the absorption ratio threshold JKyz, an insulation abnormality signal of the power distribution equipment is generated.

[0008] As a further solution of the present invention: the discharge coefficient is FIB i The way to obtain is: B1: Perform discharge current detection on the discharge detection area i on the surface of the power distribution equipment to obtain the regional discharge detection current value I of the discharge detection area within the discharge detection cycle time FT （FT） Then, the rectangular coordinates are established with the regional discharge detection current value as the ordinate and the discharge detection time as the abscissa to obtain the regional current change curve from the detection initial time FTz to the detection end time FTm within the discharge detection cycle FT, and recorded as Q （i） ; B2: Based on the regional current variation curve Q in the discharge detection area （i） ; Get the current band values ​​in the regional current change curve and mark them as j in turn, where j is a non-negative integer; at the same time, get the duration of each current band based on the regional current change curve and mark it as BT （i，j） ; At the same time, the maximum current value in each current band is obtained and marked as Imax （i，j） ; B3: The maximum current Imax in each current band of the discharge detection area i within the discharge detection cycle FT （i，j） Compare with the detection current extreme value threshold Isa respectively; Get the maximum current Imax of the discharge detection area i in the discharge detection cycle FT （i，j） The number of band currents greater than the detection current extreme value threshold Isa is marked as m; B4: Pass Calculate the discharge coefficient ratio FIB of the discharge detection area i i .

[0009] As a further solution of the present invention: the discharge coefficient is greater than FIB i Compare with the preset discharge coefficient ratio FIBin: If the discharge coefficient is greater than FIB i Less than or equal to the preset discharge coefficient ratio FIBin, generating a regional stability signal; If the discharge coefficient is greater than FIB i If it is greater than the preset discharge coefficient ratio FIBin, a regional abnormality signal is generated.

[0010] As a further solution of the present invention: the discharge amount risk fluctuation performance extreme value QI i Compared with the discharge safety value Qan: If the discharge risk fluctuation shows extreme value QI i Greater than or equal to the discharge safety value Qan; generating a discharge risk signal; If the discharge risk fluctuation shows extreme value QI i Less than the discharge safety value Qan; a discharge warning signal is generated.

[0011] As a further solution of the present invention: the temperature abnormal area ratio SB i The way to obtain is: Step C1: Divide the temperature distribution image of the discharge detection area i into grids of length kXk and mark them as f; where f is 1, 2, 3, ...; obtain the initial temperature value at the initial detection time FTz; C2: After the discharge detection cycle FT, the vertex temperature value of each grid at the detection end time FTm is obtained, and the vertex temperature change value of each grid is obtained by subtracting the vertex temperature value of each grid at the detection end time FTm from the initial temperature value at the detection initial time FTz; C3: Compare the vertex temperature change value of each mesh with the temperature change threshold; obtain the number of vertex temperature change values ​​of each mesh that are greater than the temperature change threshold and mark them as WY f ; pass Calculate and obtain the temperature anomaly area value Swy of the grid f in the discharge detection area i f ; C4: Then, through Calculate the temperature difference ratio SB of the discharge detection area i i .

[0012] As a further solution of the present invention: the temperature isotope ratio SB i Compared with the extreme value SBJ of temperature heterogeneity ratio: If the temperature is different than SB i If it is greater than or equal to the extreme value of the temperature heterogeneity ratio SBJ, a thermal anomaly signal is generated; If the temperature is different than SB i When the temperature is smaller than the extreme value SBJ of the temperature heterogeneity ratio, a thermal stability signal is generated.

[0013] As a further solution of the present invention: a system for evaluating insulation latent faults of power distribution equipment, comprising: Data acquisition module: used to measure the insulation resistance value of the external insulation material of the power distribution equipment with a megohmmeter, and calculate the absorption ratio JK of the insulation material based on the measured insulation resistance value; and compare it with the absorption ratio threshold JKyz; obtain the insulation stability signal of the power distribution equipment or the insulation abnormality signal of the power distribution equipment; Insulation processing module: Based on the insulation abnormality signal of the distribution equipment, the surface of the distribution equipment is divided into several discharge detection areas, and the discharge detection areas are marked as i, where i is 1, 2, 3...; discharge detection is performed on the discharge detection areas on the surface of the distribution equipment, and the discharge coefficient ratio FIB of the discharge detection areas is calculated. i; and compare with the preset discharge coefficient ratio FIBin; obtain regional stability signal or regional abnormal signal; Discharge assessment module: Based on regional abnormal signals, obtain the regional current change curve Q of the surface discharge detection area of ​​the distribution equipment （i） ; pass Calculate the discharge amount GDF of the discharge detection area i i ; Then through Calculate and obtain the discharge amount risk fluctuation extreme value QI of the discharge detection area i i ; Then the discharge risk fluctuation performance extreme value QI i Compare with the discharge amount safety value Qan; obtain a discharge risk signal or a discharge warning signal; Temperature evaluation module: Based on the discharge warning signal, the temperature of the discharge detection area i is detected by the infrared thermal imaging sensor to obtain the temperature distribution image of the discharge detection area i; the temperature heterogeneity ratio SB in the discharge detection area i is calculated i ; Then compare it with the temperature heterogeneity ratio extreme value SBJ; obtain thermal anomaly signal or thermal stability signal.

[0014] Beneficial effects of the present invention: In the present invention, the surface insulating material of the power distribution equipment is divided into discharge detection areas, pulse current detection is performed on each discharge detection area, and the current change on the insulating material within the discharge detection cycle is detected. Based on the regional discharge detection current on the surface of the insulating material and the current band change, the discharge insulation performance of the insulating material is judged. At the same time, based on the discharge coefficient ratio and the discharge amount in the discharge detection area, the current band of the insulating material in the discharge detection area is calculated for continuity, the maximum discharge amount of the insulating material in the discharge detection area is calculated, and then it is judged whether it is safe outside the discharge detection area; Under the discharge warning signal in the discharge detection area, the temperature of the discharge detection area is detected to detect the temperature change state of the insulating material in the discharge detection area during the discharge detection process, so as to detect whether the temperature change of the insulating material is abnormal when the external insulating equipment of the distribution equipment fluctuates during operation, so as to avoid the safety risk caused by heating of the insulating material and discharge of the distribution equipment. When evaluating and calculating the insulation during the operation of the distribution equipment, fault assessment is carried out based on the insulation state, discharge amount and operating temperature of the insulating material outside the distribution equipment, so as to discover and solve the insulation fault of the distribution equipment in advance, ensure the stable and normal operation of the equipment, and avoid the problem of inaccurate detection caused by manual detection and evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings.

[0016] Figure 1 It is a schematic flow chart of the method of the present invention; Figure 2 It is a system block diagram of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Embodiment 1

[0018] See also Figure 1 As shown, the present invention is a method for evaluating latent insulation faults of power distribution equipment, comprising: Step 1: Use a megohmmeter to measure the insulation resistance value of the external insulation material of the power distribution equipment, and calculate the absorption ratio JK of the insulation material based on the measured insulation resistance value; The calculation process of the absorption ratio JK is: A11: Connect a DC voltage with a voltage value of KU to the insulation material of the power distribution equipment, and then use a megohmmeter to perform periodic insulation resistance testing on the power distribution equipment; Specifically, the process of periodic insulation resistance detection is to set the external DC voltage of the power distribution equipment as the starting time 0, and the unit time t as the detection time interval, and divide the insulation resistance detection period RT into several detection time points, which are marked as n respectively, where n is 1, 2, 3...; A12: Get the detection current value at each detection time point n within the insulation resistance detection cycle T and mark it as JI n ; A13: Pass Calculate and obtain the insulation resistance value JR of the power distribution equipment at each detection time point n n ; A14: Obtain the insulation resistance values ​​at the initial state time point ct and the final state time point wt within the insulation resistance detection period T, and mark them as initial state resistance values ​​JR ct and final resistance JR wt ; It should be noted that the initial state time point and the final state time point are usually two relatively accurate time points in the process of insulation resistance value detection from the beginning to the end, such as the two time points of 10 seconds and 50 seconds. The specific time points are determined based on the working environment and application scenarios of the distribution equipment. Usually, the absorption ratio calculated at these two time points can measure the insulation stability of the insulation material during the working process of the distribution equipment; pass Calculate and obtain the absorption ratio JK of the insulating material; Step 2: Compare the absorption ratio JK of the insulation material of the power distribution equipment with the absorption ratio threshold JKyz; If the absorption ratio JK of the insulation material of the power distribution equipment is greater than or equal to the absorption ratio threshold JKyz, a power distribution equipment insulation stability signal is generated; If the absorption of the insulating material on the power distribution equipment is relatively large, it means that the insulating effect of the insulating material is good. When the power distribution equipment is working, the insulation resistance can be increased quickly to ensure the stable operation of the power distribution equipment. If the absorption ratio JK of the insulation material of the power distribution equipment is less than the absorption ratio threshold JKyz, an insulation abnormality signal of the power distribution equipment is generated; at this time, it means that the insulation material of the power distribution equipment has an abnormality during operation, so that the insulation material cannot meet the insulation requirements during the operation of the power distribution equipment, and further detection of the abnormality of the insulation material is required; Step 3: Based on the insulation abnormality signal of the distribution equipment, the surface of the distribution equipment is divided into several discharge detection areas, and the discharge detection areas are marked as i, where i is 1, 2, 3...; discharge detection is performed on the discharge detection areas on the surface of the distribution equipment, and during the discharge detection process, a high-frequency current sensor is used to perform a pulse current detection with a discharge detection cycle length of FT on the discharge detection areas on the surface of the distribution equipment; the discharge coefficient ratio FIB of the discharge detection area is calculated i ; The specific steps include: B1: Perform discharge current detection on the discharge detection area i on the surface of the power distribution equipment to obtain the regional discharge detection current value I of the discharge detection area within the discharge detection cycle time FT （FT） Then, a rectangular coordinate system is established with the regional discharge detection current value as the ordinate and the discharge detection time as the abscissa to obtain the regional current change curve from the detection initial time FTz to the detection end time FTm within the discharge detection cycle FT, and recorded as Q （i） ; B2: Based on the regional current variation curve Q in the discharge detection area （i） ; Get the current band values ​​in the regional current change curve and mark them as j in turn, where j is a non-negative integer; at the same time, get the duration of each current band based on the regional current change curve and mark it as BT （i，j） ; At the same time, the maximum current value in each current band is obtained and marked as Imax （i，j） ; It should be noted that: the current band refers to the change curve of the regional current in the discharge detection area from zero to zero between the detection initial time FTz and the detection end time FTm; B3: The maximum current Imax in each current band of the discharge detection area i within the discharge detection cycle FT （i，j） Compare with the detection current extreme value threshold Isa respectively; Get the maximum current Imax of the discharge detection area i in the discharge detection cycle FT （i，j） The number of band currents greater than the detection current extreme value threshold Isa is marked as m; B4: Pass Calculate the discharge coefficient ratio FIB of the discharge detection area i i ; By dividing the insulating material on the surface of the distribution equipment into discharge detection areas, pulse current detection is performed on each discharge detection area, and the current change on the insulating material during the discharge detection cycle is detected. Based on the regional discharge detection current and current band change on the surface of the insulating material, the discharge coefficient ratio is calculated and obtained. This can be used to determine the proportion of discharge time of the insulating material during the working time of the distribution equipment during the staged working process of the distribution equipment; Step 4: Compare the discharge coefficient to FIB i Compare with the preset discharge coefficient ratio FIBin; If the discharge coefficient is greater than FIB i Less than or equal to the preset discharge coefficient ratio FIBin, a regional stability signal is generated; this indicates that the proportion of discharge time and discharge fluctuation on the surface of the insulating material during the discharge detection test are small, that is, the insulating material in the discharge detection area is relatively stable; If the discharge coefficient is greater than FIB i If the discharge coefficient is greater than the preset ratio FIBin, a regional abnormality signal is generated; this indicates that the insulation effect of the insulating material in the region is poor during the discharge detection process, and more discharge current fluctuations occur. At this time, it indicates that material abnormalities occur in the discharge detection region of the insulating material, which may be manifested as aging or cracking of the insulating material; Step 5: Based on the regional abnormal signal, obtain the regional current change curve Q of the surface discharge detection area of ​​the distribution equipment （i） ; pass Calculate the discharge amount GDF of the discharge detection area i i ; Then through Calculate and obtain the discharge amount risk fluctuation extreme value QI of the discharge detection area i i ; Based on the discharge coefficient ratio and the discharge amount in the discharge detection area, the current band of the insulating material in the discharge detection area is calculated to be continuous, the maximum discharge amount of the insulating material in the discharge detection area is calculated, and then it is determined whether it is safe outside the discharge detection area; It should be noted that the calculation method of the extreme value of the electric quantity risk fluctuation is to make a continuity assumption on the current fluctuation on the insulating material during the discharge current detection process to calculate the maximum discharge amount that may occur in the discharge detection area, so as to ensure to the greatest extent that there will be no discharge risk in the discharge detection area; Then the discharge risk fluctuation performance extreme value QI i Compare with the discharge capacity safety value Qan; If the discharge risk fluctuation shows extreme value QI i Greater than or equal to the discharge safety value Qan; a discharge risk signal is generated; at this time, it means that continuous discharge may occur in the discharge detection area, resulting in excessive discharge, and thus a risk hazard; If the discharge risk fluctuation shows extreme value QI i is less than the discharge safety value Qan; a discharge warning signal is generated; at this time, a discharge warning is given to the discharge detection area, and the insulating material of the discharge detection area is checked; Step 6: Based on the discharge warning signal, the temperature of the discharge detection area i is detected by an infrared thermal imaging sensor to obtain a temperature distribution image of the discharge detection area i; and the temperature heterogeneity ratio SB in the discharge detection area i is calculated based on the temperature distribution image. i ; Specifically, regarding the temperature anomaly area ratio SB i The way to obtain is: Step C1: Divide the temperature distribution image of the discharge detection area i into grids of length kXk and mark them as f; where f is 1, 2, 3, ...; obtain the initial temperature value at the initial detection time FTz; C2: After the discharge detection cycle FT, the vertex temperature value of each grid at the detection end time FTm is obtained, and the vertex temperature change value of each grid is obtained by subtracting the vertex temperature value of each grid at the detection end time FTm from the initial temperature value at the detection initial time FTz; C3: Compare the vertex temperature change value of each mesh with the temperature change threshold; obtain the number of vertex temperature change values ​​of each mesh that are greater than the temperature change threshold and mark them as WY f ; pass Calculate and obtain the temperature anomaly area value Swy of the grid f in the discharge detection area i f ; C4: Then, through Calculate the temperature difference ratio SB of the discharge detection area i i ; Step 7: Compare the temperature to SB i Compare with the extreme value of temperature allotropy ratio SBJ; If the temperature is different than SB i If it is greater than or equal to the extreme value of the temperature heterogeneity ratio SBJ, a thermal anomaly signal is generated; If the temperature is different than SB i When the temperature is smaller than the extreme value SBJ of the temperature heterogeneity ratio, a thermal stability signal is generated.

[0019] Under the discharge warning signal in the discharge detection area, the temperature of the discharge detection area is detected to detect the temperature change state of the insulating material in the discharge detection area during the discharge detection process, so as to detect whether the temperature change of the insulating material is abnormal when the external insulating equipment of the distribution equipment fluctuates during the operation of the distribution equipment, so as to avoid the safety risks caused by the heating of the insulating material and the discharge of the distribution equipment. When evaluating and calculating the insulation during the operation of the distribution equipment, the fault assessment is carried out based on the insulation state, discharge amount and operating temperature of the insulating material outside the distribution equipment, so as to discover and solve the insulation fault of the distribution equipment in advance, ensure the stable and normal operation of the equipment, and avoid the problem of inaccurate detection caused by manual detection and evaluation. Embodiment 2

[0020] Reference Figure 2 As shown, a system for evaluating insulation latent faults of power distribution equipment comprises: Data acquisition module: used to measure the insulation resistance value of the external insulation material of the power distribution equipment with a megohmmeter, and calculate the absorption ratio JK of the insulation material based on the measured insulation resistance value; and compare it with the absorption ratio threshold JKyz; obtain the insulation stability signal of the power distribution equipment or the insulation abnormality signal of the power distribution equipment; Insulation processing module: Based on the insulation abnormality signal of the distribution equipment, the surface of the distribution equipment is divided into several discharge detection areas, and the discharge detection areas are marked as i, where i is 1, 2, 3...; discharge detection is performed on the discharge detection areas on the surface of the distribution equipment, and the discharge coefficient ratio FIB of the discharge detection areas is calculated. i ; and compare with the preset discharge coefficient ratio FIBin; obtain regional stability signal or regional abnormal signal; Discharge assessment module: Based on regional abnormal signals, obtain the regional current change curve Q of the surface discharge detection area of ​​the distribution equipment （i） ; pass Calculate the discharge amount GDF of the discharge detection area i i ; Then through Calculate and obtain the discharge amount risk fluctuation extreme value QI of the discharge detection area i i ; Then the discharge risk fluctuation performance extreme value QI i Compare with the discharge amount safety value Qan; obtain a discharge risk signal or a discharge warning signal; Temperature evaluation module: Based on the discharge warning signal, the temperature of the discharge detection area i is detected by the infrared thermal imaging sensor to obtain the temperature distribution image of the discharge detection area i; the temperature heterogeneity ratio SB in the discharge detection area i is calculated i ; Then compare it with the temperature heterogeneity ratio extreme value SBJ; obtain thermal anomaly signal or thermal stability signal.

[0021] Under the discharge warning signal in the discharge detection area, the temperature of the discharge detection area is detected to detect the temperature change state of the insulating material in the discharge detection area during the discharge detection process, so as to detect whether the temperature change of the insulating material is abnormal when the external insulating equipment of the distribution equipment fluctuates during operation, so as to avoid the safety risk caused by heating of the insulating material and discharge of the distribution equipment. When evaluating and calculating the insulation during the operation of the distribution equipment, fault evaluation is carried out based on the insulation state, discharge amount and operating temperature of the insulating material outside the distribution equipment, so as to discover and solve the insulation fault of the distribution equipment in advance and ensure the stable and normal operation of the equipment.

[0022] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for evaluating latent insulation faults of power distribution equipment, characterized in that: include: The insulation resistance value of the external insulation material of the power distribution equipment is measured by using a megohmmeter, and the absorption ratio JK of the insulation material is calculated based on the measured insulation resistance value; And compare it with the absorption ratio threshold JKyz to obtain the insulation stability signal of the distribution equipment or the insulation abnormality signal of the distribution equipment; Based on the insulation abnormality signal of the distribution equipment, the surface of the distribution equipment is divided into several discharge detection areas, and the discharge detection areas are marked as i, where i is 1, 2, 3...; discharge detection is performed on the discharge detection areas on the surface of the distribution equipment, and the discharge coefficient ratio FIB of the discharge detection area is calculated. i ; and compare with the preset discharge coefficient ratio FIBin; obtain regional stability signal or regional abnormal signal; Based on the regional abnormal signal, obtain the regional current change curve Q of the surface discharge detection area of ​​the distribution equipment （i） ; pass Calculate the discharge amount GDF of the discharge detection area i i ; Then through Calculate and obtain the discharge amount risk fluctuation extreme value QI of the discharge detection area i i ; Then the discharge risk fluctuation performance extreme value QI i Compare with the discharge amount safety value Qan; obtain a discharge risk signal or a discharge warning signal; Based on the discharge warning signal, the temperature of the discharge detection area i is detected by an infrared thermal imaging sensor to obtain the temperature distribution image of the discharge detection area i; the temperature heterogeneity ratio SB in the discharge detection area i is calculated. i ; Then compare it with the temperature heterogeneity ratio extreme value SBJ; obtain thermal anomaly signal or thermal stability signal.

2. A method for evaluating latent insulation faults of power distribution equipment according to claim 1, characterized in that: The calculation process of the absorption ratio JK is: A11: Connect a DC voltage with a voltage value of KU to the insulation material of the power distribution equipment, and then use a megohmmeter to perform periodic insulation resistance testing on the power distribution equipment; A12: Get the detection current value at each detection time point n within the insulation resistance detection cycle T and mark it as JI n ; A13: Pass Calculate and obtain the insulation resistance value JR of the power distribution equipment at each detection time point n n ; A14: Obtain the insulation resistance values ​​at the initial state time point ct and the final state time point wt within the insulation resistance detection period T, and mark them as initial state resistance values ​​JR ct and final resistance JR wt ; pass Calculate the absorption ratio JK of the insulating material.

3. A method for evaluating latent insulation faults of power distribution equipment according to claim 2, characterized in that: The process of the periodic insulation resistance detection is to take the external DC voltage of the distribution equipment as the starting time 0, the unit time t as the detection time interval, and divide the insulation resistance detection period RT into several detection time points, which are marked as n respectively, where n is 1, 2, 3...

4. A method for evaluating latent insulation faults of power distribution equipment according to claim 3, characterized in that: Compare the absorption ratio JK of the insulation material of the power distribution equipment with the absorption ratio threshold JKyz: If the absorption ratio JK of the insulation material of the power distribution equipment is greater than or equal to the absorption ratio threshold JKyz, a power distribution equipment insulation stability signal is generated; If the absorption ratio JK of the insulation material of the power distribution equipment is less than the absorption ratio threshold JKyz, an insulation abnormality signal of the power distribution equipment is generated.

5. A method for evaluating latent insulation faults of power distribution equipment according to claim 1, characterized in that: The discharge coefficient is higher than FIB i The way to obtain is: B1: Perform discharge current detection on the discharge detection area i on the surface of the power distribution equipment to obtain the regional discharge detection current value I of the discharge detection area within the discharge detection cycle time FT （FT） Then, a rectangular coordinate system is established with the regional discharge detection current value as the ordinate and the discharge detection time as the abscissa to obtain the regional current change curve from the detection initial time FTz to the detection end time FTm within the discharge detection cycle FT, and recorded as Q （i） ; B2: Based on the regional current variation curve Q in the discharge detection area （i） ; Get the current band values ​​in the regional current change curve and mark them as j in turn, where j is a non-negative integer; at the same time, get the duration of each current band based on the regional current change curve and mark it as BT （i，j） ; At the same time, the maximum current value in each current band is obtained and marked as Imax （i，j） ; B3: The maximum current Imax in each current band of the discharge detection area i within the discharge detection cycle FT （i，j） Compare with the detection current extreme value threshold Isa respectively; Get the maximum current Imax of the discharge detection area i in the discharge detection cycle FT （i，j） The number of band currents greater than the detection current extreme value threshold Isa is marked as m; B4: Pass Calculate the discharge coefficient ratio FIB of the discharge detection area i i .

6. A method for evaluating latent insulation faults of power distribution equipment according to claim 5, characterized in that: The discharge coefficient is compared to FIB i Compare with the preset discharge coefficient ratio FIBin: If the discharge coefficient is greater than FIB i Less than or equal to the preset discharge coefficient ratio FIBin, generating a regional stability signal; If the discharge coefficient is greater than FIB i If it is greater than the preset discharge coefficient ratio FIBin, a regional abnormality signal is generated.

7. A method for evaluating latent insulation faults of power distribution equipment according to claim 1, characterized in that: The discharge risk fluctuation shows the extreme value QI i Compared with the discharge safety value Qan: If the discharge risk fluctuation shows extreme value QI i Greater than or equal to the discharge safety value Qan; generating a discharge risk signal; If the discharge risk fluctuation shows extreme value QI i Less than the discharge safety value Qan; a discharge warning signal is generated.

8. A method for evaluating latent insulation faults of power distribution equipment according to claim 1, characterized in that: The temperature abnormal area ratio SB i The way to obtain is: Step C1: Divide the temperature distribution image of the discharge detection area i into grids of length kXk and mark them as f; where f is 1, 2, 3, ...; obtain the initial temperature value at the initial detection time FTz; C2: After the discharge detection cycle FT, the vertex temperature value of each grid at the detection end time FTm is obtained, and the vertex temperature change value of each grid is obtained by subtracting the vertex temperature value of each grid at the detection end time FTm from the initial temperature value at the detection initial time FTz; C3: Compare the vertex temperature change value of each mesh with the temperature change threshold; obtain the number of vertex temperature change values ​​of each mesh that are greater than the temperature change threshold and mark them as WY f ; pass Calculate and obtain the temperature anomaly area value Swy of the grid f in the discharge detection area i f ; C4: Then, through Calculate the temperature difference ratio SB of the discharge detection area i i .

9. A method for evaluating latent insulation faults of power distribution equipment according to claim 8, characterized in that: Compare the temperature to SB i Compared with the extreme value SBJ of temperature heterogeneity ratio: If the temperature is different than SB i If it is greater than or equal to the extreme value of the temperature heterogeneity ratio SBJ, a thermal anomaly signal is generated; If the temperature is different than SB i When the temperature is less than the extreme value SBJ of the temperature heterogeneity ratio, a thermal stability signal is generated.

10. A system for evaluating latent insulation faults of power distribution equipment, characterized in that: The system is used to perform the evaluation method as described in any one of claims 1 to 9, comprising: Data acquisition module: used to measure the insulation resistance value of the external insulation material of the power distribution equipment with a megohmmeter, and calculate the absorption ratio JK of the insulation material based on the measured insulation resistance value; and compare it with the absorption ratio threshold JKyz; obtain the insulation stability signal of the power distribution equipment or the insulation abnormality signal of the power distribution equipment; Insulation processing module: Based on the insulation abnormality signal of the distribution equipment, the surface of the distribution equipment is divided into several discharge detection areas, and the discharge detection areas are marked as i, where i is 1, 2, 3...; discharge detection is performed on the discharge detection areas on the surface of the distribution equipment, and the discharge coefficient ratio FIB of the discharge detection areas is calculated. i ; and compare with the preset discharge coefficient ratio FIBin; obtain regional stability signal or regional abnormal signal; Discharge assessment module: Based on regional abnormal signals, obtain the regional current change curve Q of the surface discharge detection area of ​​the distribution equipment （i） ; pass Calculate the discharge amount GDF of the discharge detection area i i ; Then through Calculate and obtain the discharge amount risk fluctuation extreme value QI of the discharge detection area i i ; Then the discharge risk fluctuation performance extreme value QI i Compare with the discharge amount safety value Qan; obtain a discharge risk signal or a discharge warning signal; Temperature evaluation module: Based on the discharge warning signal, the temperature of the discharge detection area i is detected by the infrared thermal imaging sensor to obtain the temperature distribution image of the discharge detection area i; the temperature heterogeneity ratio SB in the discharge detection area i is calculated i ; Then compare it with the temperature heterogeneity ratio extreme value SBJ; obtain thermal anomaly signal or thermal stability signal.

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