Method, system and equipment for predicting failure time of basin-type insulator under extreme working condition

Abstract

The invention relates to the technical field of electrical equipment state evaluation, and discloses a basin-type insulator failure time prediction method, system and equipment under an extreme working condition, and the method comprises the steps: building a basin-type insulator model according to the characteristics of a target basin-type insulator and a corresponding extreme load, and carrying out the prediction of the failure time of the basin-type insulator; setting a crack on the basin-type insulator model and carrying out crack propagation simulation, when the crack of the basin-type insulator model enters a rapid propagation stage, obtaining the duration for the crack to enter the rapid propagation stage, and predicting the failure time of the target basin-type insulator under the extreme working condition according to the duration; according to the method, when the target basin-type insulator is going to experience or already experienced the extreme working condition, crack propagation simulation can be carried out according to the target basin-type insulator characteristic data collected before the target basin-type insulator experiences the extreme working condition and in combination with the extreme load to predict the failure time; and the prediction accuracy of the failure time of the basin-type insulator under the extreme condition and the effectiveness of formulating a preventive maintenance plan of the basin-type insulator are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical equipment status assessment, and in particular to a method, system and device for predicting the failure time of a pot-type insulator under extreme working conditions. Background Art

[0002] Pan insulators are indispensable components inside gas insulated switchgear (GIS). They mainly play the role of mechanical fixation, electrical insulation and gas isolation. They are usually made of ceramic materials or synthetic materials (such as epoxy resin, silicone rubber, etc.).

[0003] However, the crack defects that may appear in the pot insulator will weaken the mechanical strength of the pot insulator, and then threaten the overall stability and electrical performance of the pot insulator: the temperature change during the production and curing of the pot insulator and the mechanical extrusion of the central conductor and the shell make the pot insulator bear huge internal stress, which may cause tiny cracks on its surface; the pot insulator is prone to force imbalance during transportation and installation; the ambient temperature difference during the operation of the pot insulator is prone to the gradual expansion and discharge of internal pores; the pot insulator bears complex electrical, thermal, mechanical and other stresses for a long time; under the induction of the above factors, the surface and / or interior of the pot insulator are prone to cracks, which will distort the internal field strength of the pot insulator. Once the local electric field exceeds the limit, discharge will occur, which seriously threatens the safe and stable operation of the power system, and the crack expansion is easy to cause the pot insulator to fail. Therefore, in order to ensure the safety and reliability of pot insulators, it is very necessary to carry out research on the crack initiation and expansion behavior of pot insulators.

[0004] Scholars have conducted a lot of research on material crack propagation and have achieved certain results, but most of these studies focus on general materials and conventional use conditions. In actual operating environments, pot insulators not only have to withstand normal electrical and mechanical loads, but may also encounter extreme environmental conditions, such as typhoons, earthquakes, icing and other emergencies. The loads generated by these extreme conditions will significantly increase the stress concentration inside the pot insulator, accelerate the expansion of existing micro cracks, and ultimately lead to material failure. At present, there are few studies on the life prediction of pot insulators under extreme environmental conditions, which makes the accuracy of predicting the failure time of pot insulators under extreme conditions poor, resulting in low effectiveness of the preventive maintenance plan for pot insulators and high safety risks of sudden failures. Summary of the invention

[0005] The present invention provides a method, system and device for predicting the failure time of a pot-type insulator under extreme working conditions, which solves the technical problem of poor accuracy in predicting the failure time of a pot-type insulator under extreme conditions.

[0006] A first aspect of the present invention provides a method for predicting failure time of a pot-type insulator under extreme working conditions, comprising:

[0007] According to the characteristics of the target pot insulator and the corresponding extreme loads, a pot insulator model is constructed;

[0008] Set cracks on the pot insulator model and perform crack propagation simulation;

[0009] When the crack of the pot-type insulator model enters the rapid expansion stage, obtaining the time taken for the crack to enter the rapid expansion stage;

[0010] The failure time of the target pot-type insulator under extreme working conditions is predicted according to the duration.

[0011] Optionally, constructing a pot-type insulator model according to the characteristics of the target pot-type insulator and the corresponding extreme loads specifically includes:

[0012] According to the characteristics of the target pot insulator, an initial model is constructed;

[0013] Apply extreme loads to the initial model to obtain the pot insulator model.

[0014] Optionally, the extreme load includes an earthquake load; if the earthquake does not occur, the method further comprises:

[0015] According to the corresponding site characteristics of the target pot-type insulator, the design response spectrum is obtained;

[0016] The response acceleration spectrum is calculated by using the design response spectrum combined with the response spectrum analysis method;

[0017] The response acceleration spectrum is convolved with the structural characteristics of the target pot-type insulator to calculate the seismic load of the target pot-type insulator.

[0018] Optionally, after convolving the response acceleration spectrum with the structural characteristics of the target pot-type insulator to calculate the seismic load of the target pot-type insulator, the method further includes:

[0019] According to the stress ratio of the target pot insulator, the seismic load corresponding to the stress ratio is extracted from the seismic load.

[0020] Optionally, the extreme load includes an earthquake load; if an earthquake has occurred, the method further comprises:

[0021] Obtain the actual acceleration time history data of the earthquake that has occurred;

[0022] The actual acceleration time history data is convolved with the structural characteristics of the target pot-type insulator to calculate the seismic load of the target pot-type insulator.

[0023] Optionally, the extreme load includes a typhoon load; then the method further includes:

[0024] The wind speed spectrum is calculated using the Davenport wind speed spectrum formula using typhoon data and the corresponding site characteristics of the target pot insulator.

[0025] The wind speed spectrum is used to simulate the pulsating wind speed time history through the harmonic synthesis method;

[0026] According to the air density, pulsating wind speed time history and the wind characteristics of the target pot insulator, the instantaneous wind load of the target pot insulator under the corresponding typhoon level is calculated.

[0027] Optionally, after calculating the instantaneous wind load of the target pot-type insulator under the corresponding typhoon level according to the air density, the pulsating wind speed time history and the wind-receiving characteristics of the target pot-type insulator, the method further includes:

[0028] According to the stress ratio of the target pot insulator, a section corresponding to the stress ratio is cut from the instantaneous wind load as the typhoon load.

[0029] A second aspect of the present invention provides a system for predicting failure time of a pot-type insulator under extreme working conditions, comprising:

[0030] A model building module is used to build a pot insulator model according to the characteristics of the target pot insulator and the corresponding extreme loads;

[0031] Crack propagation simulation module, used to set cracks on the pot insulator model and perform crack propagation simulation;

[0032] A data acquisition module, used for acquiring the time taken for the crack to enter the rapid expansion stage when the crack of the pot-type insulator model enters the rapid expansion stage;

[0033] A prediction module is used to predict the failure time of the target pot-type insulator under extreme working conditions according to the duration.

[0034] A third aspect of the present invention provides a device for predicting the failure time of a pot-type insulator under extreme working conditions, comprising a processor and a memory;

[0035] The memory is used to store program codes and transmit the program codes to the processor;

[0036] The processor is used to execute the method for predicting the failure time of a pot-type insulator under extreme working conditions as described in any one of the above items according to the instructions in the program code.

[0037] A fourth aspect of the present invention provides a storage medium, wherein the storage medium is used to store program code, and the program code is used to execute the method for predicting the failure time of a pot-type insulator under extreme working conditions described in any one of the above items.

[0038] It can be seen from the above technical solutions that the present invention has the following advantages:

[0039] The present invention provides a method, system, device and storage medium for predicting the failure time of a pot-type insulator under extreme working conditions, wherein the method comprises: constructing a pot-type insulator model according to the characteristics of a target pot-type insulator and a corresponding extreme load, setting a crack on the pot-type insulator model and performing crack extension simulation, obtaining the time taken for the crack to enter the rapid extension stage when the crack of the pot-type insulator model enters a rapid extension stage, and predicting the failure time of the target pot-type insulator under extreme working conditions according to the time; in the practical application of the method for predicting the failure time of a pot-type insulator under extreme working conditions provided by the present invention, when the target pot-type insulator is about to experience or has experienced an extreme working condition, a model can be constructed according to characteristic data of the target pot-type insulator collected before experiencing the extreme working condition and in combination with an extreme load calculated from predicted data or actual data of the extreme working condition, and then predicting the failure time of the target pot-type insulator under extreme working conditions through crack extension simulation, thereby improving the accuracy of predicting the failure time of the pot-type insulator under extreme conditions and the effectiveness of formulating a preventive maintenance plan for the pot-type insulator, reducing the safety risk of sudden failure of the pot-type insulator, and ensuring the safe operation of power equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0041] Figure 1 A flowchart of a method for predicting the failure time of a pot-type insulator under extreme working conditions provided by an embodiment of the present invention;

[0042] Figure 2 A schematic diagram of the time-stepping simulation expansion step provided by an embodiment of the present invention;

[0043] Figure 3 is a curve diagram showing the stress intensity factor changing with the crack extension length provided by an embodiment of the present invention;

[0044] Figure 4 A flowchart of a method for predicting the failure time of a pot-type insulator under extreme working conditions provided by an embodiment of the present invention;

[0045] Figure 5 is a fatigue crack growth rate curve under earthquake conditions provided by an embodiment of the present invention;

[0046] Figure 6is a fatigue crack growth rate curve under typhoon conditions provided by an embodiment of the present invention;

[0047] Figure 7 A schematic diagram of crack types provided by an embodiment of the present invention;

[0048] Figure 8 A schematic diagram of a 90° crack expansion path provided by an embodiment of the present invention;

[0049] Fig. 9 A schematic diagram of a 135° crack propagation path provided by an embodiment of the present invention;

[0050] Fig.10 A schematic diagram of the expansion path of a rectangular crack provided by an embodiment of the present invention;

[0051] Fig.11 A schematic diagram of the expansion path of a semicircular crack provided by an embodiment of the present invention;

[0052] Fig.12 A schematic diagram of the expansion path of a 1 / 4 circular crack provided in an embodiment of the present invention;

[0053] Fig.13 A histogram of fatigue crack growth life at different stress ratios under earthquake conditions provided by an embodiment of the present invention;

[0054] Fig.14 A histogram of fatigue crack growth life at different stress ratios under typhoon conditions provided by an embodiment of the present invention;

[0055] Fig.15 A histogram of fatigue crack growth life at different initial crack deflection angles under earthquake conditions provided by an embodiment of the present invention;

[0056] Fig.16 A histogram of fatigue crack growth life at different initial crack deflection angles under typhoon conditions provided by an embodiment of the present invention;

[0057] Fig.17 A histogram of fatigue crack growth life of different crack shapes under earthquake conditions provided by an embodiment of the present invention;

[0058] Fig.18 A histogram of fatigue crack growth life of different crack shapes under typhoon conditions provided by an embodiment of the present invention;

[0059] Fig.19 A fatigue life impact duration table of different influencing factors under earthquake conditions provided by an embodiment of the present invention;

[0060] Fig. 20 A fatigue life impact duration table of different influencing factors under typhoon conditions provided by an embodiment of the present invention;

[0061] Fig.21 A comparison diagram of fatigue life impact duration under earthquake conditions and typhoon conditions under different influencing factors provided by an embodiment of the present invention;

[0062] Fig. 22 A curve diagram showing the stress intensity factor changing with crack extension length at -20°C provided in an embodiment of the present invention;

[0063] Fig.23 A curve diagram showing the stress intensity factor at 20°C as a function of crack extension length provided in an embodiment of the present invention;

[0064] Fig.24 A curve diagram showing the stress intensity factor at 60°C as a function of crack extension length provided in an embodiment of the present invention;

[0065] Fig.25 The fatigue crack growth aN curves at different temperatures provided by the embodiment of the present invention;

[0066] Fig.26 A structural block diagram of a pot-type insulator failure time prediction system under extreme working conditions provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0067] The embodiments of the present invention provide a method, system and device for predicting the failure time of a pot-type insulator under extreme working conditions, which are used to solve the technical problem of poor accuracy in predicting the failure time of a pot-type insulator under extreme conditions.

[0068] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions 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 embodiments described below 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.

[0069] See also Figure 1 , a method for predicting failure time of a pot-type insulator under extreme working conditions is provided in a first embodiment of the present invention, comprising:

[0070] Step 11: Construct a pot insulator model according to the characteristics of the target pot insulator and the corresponding extreme loads.

[0071] It can be understood that the target pot insulator refers to the individual pot insulator whose remaining life (i.e., failure time) is to be predicted; the construction of the pot insulator model can be carried out in the simulation software, and the initial model is constructed according to the characteristics of the target pot insulator, and the pot insulator model is obtained after applying extreme loads.

[0072] The characteristics specifically include material characteristics, structural characteristics, etc. Material characteristics include density, Young's modulus, Poisson's ratio, plasticity characteristics and other characteristics and parameters of the materials used for the target pot-type insulators. Structural characteristics include shape, size and other structural parameters. Characteristics can also include crack characteristics. When the cracks of the target pot-type insulators are microcracks with length and width both in the micron level, the structural characteristics can be omitted when constructing the pot-type insulator model. The pot-type insulator model can be constructed by selecting appropriate length, width and height dimensions according to the size of the microcracks, thereby reducing the complexity and amount of calculation of the model. The crack characteristics of the target pot-type insulator can be obtained through detection methods such as X-rays, acoustic emission, ultrasound, and infrared thermal imaging.

[0073] In the present invention, extreme load refers to the mechanical stress generated by extreme working conditions on the target pot insulator. Extreme working conditions refer to the extreme environmental conditions that the target pot insulator will experience, such as typhoons, earthquakes, icing, etc. Earthquakes will impose irregular lateral and longitudinal seismic loads on the fixed pot insulators. Typhoons directly act on the surface of pot insulators to cause typhoon loads. Ice and snow accumulated on pot insulators will bring icing loads to the pot insulators. Extreme loads can be estimated from the predicted data of extreme working conditions (extreme working conditions have not occurred) or actual data (extreme working conditions have occurred).

[0074] Step 12: Set a crack on the pot insulator model and perform crack propagation simulation.

[0075] It should be noted that setting cracks on the pot-type insulator model can specifically be setting cracks on the pot-type insulator model according to crack characteristics on the target pot-type insulator, and the crack characteristics include crack shape, crack type, crack position, crack size, initial crack angle, crack extension direction, crack angle, etc.

[0076] This step can be directly implemented in the simulation software, or the basin insulator model can be imported into software specifically used for crack simulation and fracture mechanics analysis for simulation, and the crack propagation direction, path and rate of the epoxy resin material can be predicted; preferably, after the basin insulator model is imported into FRANC3D, in order to reduce unnecessary calculation amount of the basin insulator model, it can be segmented, and divided into a global (GLOBLE) model and a local (LOCLE) model according to the crack position, and then cracks are set on the model and crack propagation simulation is performed; when the extreme load applied is an extreme load with irregular frequency such as a typhoon load or an earthquake load, the simulation strategy of the crack propagation simulation preferably adopts time stepping simulation (refer to Figure 2 , Figure 2 Middle △a nodei is the crack increment, 50μm is the crack size), and the crack extension in each time step is solved step by step.

[0077] Step 13: When the crack of the pot-type insulator model enters the rapid expansion stage, the time taken for the crack to enter the rapid expansion stage is obtained.

[0078] During the crack propagation process, the development of the crack is mainly divided into three stages: I. Slow propagation stage, II. Stable fatigue crack propagation stage, III. Rapid propagation stage; whether the crack enters the rapid propagation stage can be judged based on fracture toughness parameters such as stress intensity factor, J integral or crack tip opening displacement: Figure 3 As shown in the figure, according to Pairs' law, in the stable crack growth stage, the stress intensity factor of the basin insulator crack growth increases with the increase of crack length. When the stress intensity factor exceeds the critical value of the stress intensity factor of the material used for the stress intensity factor (i.e., the fracture toughness), the crack begins to grow unstably and enters the rapid growth stage; in the stable crack growth stage, the J integral increases with the increase of crack length. When the J integral exceeds the critical value of the J integral of the material, the crack enters the rapid growth stage; in the stable crack growth stage, the crack tip opening displacement increases with the increase of crack length. When the crack tip opening displacement exceeds the critical value of the crack tip opening displacement of the material, the crack enters the rapid growth stage. After the crack enters the rapid expansion stage, the destruction speed of the pot-type insulator is extremely fast, which will cause the pot-type insulator to break. Therefore, the present invention sets the crack entering the rapid expansion stage as an indicator for determining the termination of the fatigue life stage. The time taken for the crack to enter the rapid expansion stage is the remaining life of the pot-type insulator after it begins to experience extreme working conditions (i.e., fatigue crack expansion life). The predicted failure time of the pot-type insulator under extreme working conditions is equal to the time when it begins to experience extreme working conditions plus the time taken for the crack to enter the rapid expansion stage.

[0079] Step 14: predict the failure time of the target pot-type insulator under extreme working conditions according to the duration.

[0080] It can be understood that the failure time can be used to evaluate whether the target pot insulator will fail during extreme working conditions experienced in the future, or to evaluate the status of the target pot insulator after experiencing extreme working conditions, provide a basis for risk assessment of the power system, and help determine the priority and frequency of inspection and maintenance to develop a more effective preventive maintenance plan.

[0081] In the actual application of the method for predicting the failure time of pot-type insulators under extreme working conditions provided in this embodiment, when the target pot-type insulator is about to experience or has experienced extreme working conditions, a model can be constructed based on the characteristic data collected before experiencing the extreme working conditions and combined with the extreme load calculated from the predicted data or actual data of the extreme working conditions, and then the failure time of the target pot-type insulator under extreme working conditions is predicted through crack propagation simulation, thereby improving the accuracy of the prediction of the failure time of the pot-type insulator under extreme conditions and the effectiveness of the formulation of the preventive maintenance plan for the pot-type insulator, reducing the safety risk of sudden failure of the pot-type insulator, and ensuring the safe operation of the power equipment.

[0082] See also Figure 4 A second embodiment of the present invention provides a method for predicting the failure time of a pot-type insulator under extreme conditions, comprising:

[0083] Step 21: Construct an initial model based on the characteristics of the target pot-type insulator.

[0084] It should be noted that in actual applications, pot insulators are usually installed in a fixed position. Therefore, after building the model, the initial model needs to be fixed according to the installation method of the target pot insulator. For example, the bottom of the initial model is fixed to simulate the installation state of the target pot insulator fixed on the supporting structure, so that the boundary conditions of the model are closer to the actual situation.

[0085] Step 22: Apply extreme loads to the initial model to obtain a pot-type insulator model.

[0086] Different types of extreme loads are applied in different directions on the initial model: seismic waves will cause horizontal movement and vertical vibration of the ground, and the seismic load is applied along the gravity direction and the horizontal direction; the typhoon load is applied along the typhoon wind direction. For example, if a typhoon blows at a certain angle, it will produce vertical and horizontal components. At this time, the typhoon load should be applied along the gravity direction and the horizontal direction; the weight of the ice will act directly downward on the pot insulator, and the direction of application of the ice load is the same as the gravity direction.

[0087] The crack propagation simulation was carried out on the pot insulator model with different crack types and the extreme load corresponding to the earthquake acceleration of 0.2g (intensity 8) or the extreme load corresponding to the super typhoon level (60m / s) was applied, and the results were obtained. Figure 5 and Figure 6 The fatigue crack growth rate curve of Figure 5 As shown in Figure 2, under earthquake conditions, as the crack extension length increases, the stress intensity factor of the model with type I crack increases approximately linearly. When the crack extends to 11 μm, the stress intensity factor reaches its maximum value. , the fatigue crack stable expansion stage ends and enters the rapid expansion stage, causing huge damage to the pot insulator; the stress intensity factor of the model with type II crack reaches the maximum value at the initial stage of crack expansion. , and then decreases to fluctuate around 0; contrast Figure 5 and Figure 6 It can be seen that the crack changes under typhoon conditions are similar to those under earthquake conditions, but the stable expansion stage of fatigue cracks is longer than that under earthquake conditions, which indirectly reflects that the degree of damage to basin insulators caused by typhoons is less than that caused by earthquakes.

[0088] As for the specific method of obtaining the extreme load, when the extreme working condition is an earthquake and the extreme load is an earthquake load, in a preferred embodiment, the earthquake has not occurred, and the following steps are included before step 22:

[0089] Step 2111: Obtain a design response spectrum according to the site characteristics corresponding to the target pot-type insulator.

[0090] In this step, the site characteristics specifically include the basic earthquake intensity, design basic earthquake acceleration, seismic fortification category, site category, design characteristic period, design earthquake grouping, structural damping ratio, etc. of the site where the target pot-type insulator is located; among which the basic earthquake intensity, design basic earthquake acceleration, seismic fortification category, and site category can be used to comprehensively confirm the corresponding seismic fortification intensity of the target pot-type insulator:

[0091] The design basic earthquake acceleration is the design value of the earthquake acceleration with a probability of exceeding 10% in the 50-year design reference period. The basic earthquake intensity is the intensity value corresponding to the design basic earthquake acceleration. The design characteristic period refers to the period value corresponding to the starting point of the descending segment that reflects factors such as earthquake magnitude, epicentral distance and site category. The basic earthquake intensity, design basic earthquake acceleration and design earthquake grouping can be obtained from Appendix A - Seismic fortification intensity, design basic earthquake acceleration and design earthquake grouping of major cities and towns in my country in GB50011-2010 "Code for Seismic Design of Buildings" according to the area where the target pot insulator is located. The design characteristic period and design basic earthquake acceleration can be obtained from the China seismic parameter zoning map according to the area where the target pot insulator is located.

[0092] Seismic fortification categories include special fortification category (category A), key fortification category (category B), standard fortification category (category C), etc.; in power dispatching buildings, special fortification categories include national and regional power dispatching centers, etc., and key fortification categories include power dispatching centers of provinces, autonomous regions, and municipalities directly under the central government, thermal power plants (including conventional islands of nuclear power plants), thermal power plants with a single unit capacity of 300MW and above or a planned capacity of 800MW and above in production buildings of thermal power plants (including conventional islands of nuclear power plants), and substations, and main plant buildings, electrical complex buildings, network control buildings, dispatching and communication buildings, distribution device buildings, chimneys and flues, coal crusher rooms, coal transfer stations and coal transport trestles, fuel supply facilities of oil and gas power plants, main control and communication buildings of substations of 330kV and above and hub substations of 220kV and below, and distribution device buildings of important power facilities that must maintain normal power supply during earthquakes. , local relay room, main control and communication building, valve hall and local relay room in converter station projects of 330kV and above, main power generation and distribution control room of thermal power station supplying centralized heating for towns with a population of more than 200,000 and its power supply and heating facilities, communication dispatching buildings where communication facilities should not be interrupted, etc. The standard fortification category includes other power production buildings and urban power supply facilities except special fortification category and key fortification category; the basic earthquake intensity of the area where the standard fortification category is located is the seismic fortification intensity; the seismic fortification intensity of the key fortification category should be one degree higher than the basic earthquake intensity of the area where it is located. When the basic earthquake intensity is 9 degrees, seismic measures should be taken according to requirements higher than 9 degrees; the seismic fortification intensity of the special fortification category should be one degree higher than the basic earthquake intensity of the area where it is located. When the basic earthquake intensity is 9 degrees, seismic measures should be taken according to requirements higher than 9 degrees.

[0093] The site categories are divided into four categories, namely, I, II, III and IV, according to the equivalent shear wave velocity of the soil layer and the thickness of the site cover layer (for details, please refer to Table 4.1.6 in GB50011-2010 "Code for Seismic Design of Buildings"); when the site category is I, the seismic fortification intensity of the special fortification category and the key fortification category can be equal to the basic earthquake intensity of the local area, and the seismic fortification intensity of the standard fortification category can be one degree lower than the basic earthquake intensity of the local area. When the basic earthquake intensity is 6 degrees, the seismic fortification intensity is still 6 degrees; when the site category is III or IV, for areas with a design basic earthquake acceleration of 0.15g and 0.30g, the seismic fortification intensity shall be 8 degrees (0.20g) and 9 degrees (0.40g) respectively.

[0094] The seismic fortification intensity, site category, design earthquake grouping and structural natural vibration period can be used to confirm the earthquake influence coefficient, and the design earthquake grouping and site category can be used to confirm the earthquake influence characteristic period; based on the earthquake influence coefficient and the earthquake influence characteristic period, the corresponding design response spectrum curve can be calculated and plotted, and the design response spectrum can reflect the amplification effect of seismic motion at different frequencies.

[0095] Step 2112: Use the design response spectrum in combination with the response spectrum analysis method to calculate the response acceleration spectrum.

[0096] Response spectrum analysis is a structural dynamics analysis method that can calculate the response acceleration spectrum of a structure under an earthquake. The response acceleration spectrum is the relationship between the peak acceleration response of a single-degree-of-freedom system relative to ground motion under a specific earthquake and the natural vibration period of the system.

[0097] Step 2113: Convolve the response acceleration spectrum with the structural characteristics of the target pot-type insulator to calculate the seismic load of the target pot-type insulator.

[0098] The structural characteristics of the target pot-type insulator specifically refer to the mass matrix and stiffness matrix of the structure of the target pot-type insulator.

[0099] Furthermore, step 2113 may further include:

[0100] Step 2114: According to the stress ratio of the target pot-type insulator, a section corresponding to the stress ratio is intercepted from the seismic load and the seismic load is updated.

[0101] It can be understood that the stress ratio is the ratio of the minimum load to the maximum load, and can be determined specifically based on the ratio of the highest point to the lowest point in the response acceleration spectrum. The stress-time history of seismic waves is highly nonlinear and non-stationary. The amount of complete seismic wave data is huge, and contains many frequency components. If the complete seismic load is simulated, it will be very time-consuming. By intercepting representative load segments of the seismic load according to the stress ratio and then applying them to the initial model, the complex seismic waves can be simplified into a series of representative cyclic loads, which can greatly reduce the amount of calculation and improve the simulation efficiency.

[0102] In another preferred embodiment, an earthquake has occurred, and the following steps are included before step 22:

[0103] Step 2121, obtain the actual acceleration time history data of the earthquake that has occurred.

[0104] The actual acceleration time history data is measured by a seismometer or other similar instruments.

[0105] Step 2122: Convolve the actual acceleration time history data with the structural characteristics of the target pot-type insulator to calculate the seismic load of the target pot-type insulator.

[0106] Furthermore, step 2122 may further include:

[0107] Step 2123: According to the stress ratio of the target pot-type insulator, a section corresponding to the stress ratio is intercepted from the seismic load and the seismic load is updated.

[0108] In this step, the stress ratio may be determined according to the ratio of the highest point to the lowest point of the actual acceleration time history data.

[0109] When the extreme working condition is a typhoon and the extreme load is a typhoon load, in a preferred embodiment, the following steps are included before step 22:

[0110] Step 2131, using typhoon data and site characteristics corresponding to the target pot-type insulator, and using the Davenport wind speed spectrum formula to calculate the wind speed spectrum;

[0111] In this step, typhoon data include basic wind speed, wind speed frequency data, wind direction, wind speed standard deviation, etc.; if it is a typhoon that has not occurred, the typhoon data can be obtained by analyzing the wind speed data of similar typhoons in history (in the same geographical location, season, intensity level, etc.) or using climate models for prediction; if it is a typhoon that has occurred, it can be obtained through the meteorological department; site characteristics include ground roughness coefficient, height, etc.

[0112] Step 2132: Use the wind speed spectrum to simulate the pulsating wind speed time history through the harmonic synthesis method.

[0113] This step can be performed in a programming environment, and the wind speed spectrum is converted into time series data through harmonic synthesis method. The pulsating wind speed time history can provide the time history of the instantaneous wind speed.

[0114] Step 2133, calculating the instantaneous wind load of the target pot-type insulator under the corresponding typhoon level according to the air density, the pulsating wind speed time history and the wind characteristics of the target pot-type insulator;

[0115] The wind-exposed characteristics of the target pot-type insulator include wind-exposed area, shape factor and wind pressure height variation coefficient.

[0116] The calculation formula for instantaneous wind load is:

[0117]

[0118] Where: F s is the instantaneous wind load, N; ρ is the air density, 1.235 kg / m 3 ; v is the instantaneous wind speed, m / s; u s =1.1, is the body shape coefficient; u z =1.25, which is the wind pressure height variation coefficient.

[0119] Furthermore, step 2133 may further include:

[0120] Step 2134: According to the stress ratio of the target pot-type insulator, a section corresponding to the stress ratio is cut from the instantaneous wind load as the typhoon load.

[0121] Specifically, the stress ratio may be determined according to the ratio of the highest point to the lowest point in the pulsating wind speed time history.

[0122] Step 23: Set a crack on the pot insulator model and perform crack propagation simulation.

[0123] The cracks may be arranged on the pot-type insulator model according to crack characteristics on the target pot-type insulator, wherein the crack characteristics include crack shape, crack type, crack position, crack size, initial crack angle, crack angle, crack extension direction, etc.; Fig.10 , Fig.11 and Fig.12 As shown in the figure, the crack shapes are divided into square, semicircular and 1 / 4 circular; Figure 7 As shown in the figure, according to the stress characteristics of the crack, the crack types are divided into type I (opening type), type II (sliding type) and type III (tearing type); the initial crack deflection angle refers to the offset angle of the crack relative to a reference direction (usually the main loading direction of the material or the key axis of the structure), and the crack propagation direction refers to the direction in which the crack actually propagates in the material. Figure 8 and Fig. 9 , Figure 8 and Fig. 9 The reference direction is perpendicular to the horizontal plane, and the crack propagation direction is the same. Figure 8 The initial crack deflection angle of the medium crack is 90°. Fig. 9 The initial crack deflection angle of the medium crack is 135°.

[0124] In a specific crack propagation simulation process, an initial model (size 0.2mm*0.4mm*0.05mm) was established in the simulation software and its bottom was fixed. The target pot insulator was made of epoxy resin. The material parameters were set in the simulation software according to the characteristics of epoxy resin. The density was 1.2×10 -9 tonne / mm 3 , Young's modulus is 3340MPa, Poisson's ratio is 0.3, and the Johnson-Cook constitutive model is selected as the initial model for plasticity. Extreme loads are applied to the initial model and it is segmented into GLOBLE and LOCLE models. The crack is set at the center edge of the left side of the specimen (the crack edge needs to be defined in some simulation software. Setting it at the center edge of the left side can more clearly observe the development of the crack), and the size is 0.05mm*0.02mm; Based on the above settings, the crack propagation path under earthquake or typhoon conditions is simulated by changing the stress ratio, initial crack deflection angle, and crack shape. It is found that the changes in stress ratio and initial crack deflection angle only affect the crack propagation rate, but not the crack propagation direction. The crack propagation path obtained by changing the initial crack deflection angle can be found in Figure 8 and Fig. 9 At the same time, Fig.10 , Fig.11 and Fig.12 It can be seen that the expansion rate at the tip of the square crack is relatively consistent, and the expansion length of each step is relatively uniform. However, for semicircular and 1 / 4 circular cracks, in the initial stage of crack expansion, the expansion rates at both ends of the crack front are faster than those in the middle position, and the expansion rates gradually tend to be consistent in the middle and late stages of crack expansion.

[0125] Since the number of variables under each influencing factor is different, the difference between the time taken for the crack to enter the rapid expansion stage (fatigue crack growth life) between the two variables is taken as the fatigue life influence time, and the average value of each fatigue life influence time under the same influencing factor is taken as an indicator to determine the influence degree of the influencing factor; Fig.13 The bar chart of fatigue crack growth life at different stress ratios under earthquake conditions is shown in Figure 2. Fig.14 This is a bar chart of fatigue crack growth life at different stress ratios under typhoon conditions. Fig.15 It is a bar chart of fatigue crack growth life with different initial crack deflection angles under earthquake conditions. Fig.16 This is a bar chart of fatigue crack growth life with different initial crack deflection angles under typhoon conditions. Fig.17 The bar graph of fatigue crack growth life of different crack shapes under earthquake conditions is shown in Figure 1. Fig.18 This is a bar chart of fatigue crack growth life of different crack shapes under typhoon conditions. Fig.19 This is a table showing the fatigue life impact duration of different influencing factors under earthquake conditions. Fig. 20 This is a table showing the fatigue life impact duration of different influencing factors under typhoon conditions. Fig.21 This is a comparison chart of the fatigue life impact time under earthquake conditions and typhoon conditions under different influencing factors. It can be seen that the fatigue crack extension life under different stress ratios under earthquake and typhoon extreme conditions is relatively consistent as a whole, while the average value of the fatigue life impact time under the crack shape factor is much larger than other influencing factors; the average values ​​of the fatigue life impact time are ranked: crack shape>initial crack deflection angle>stress ratio. It can be found that the stress ratio has the smallest impact, the initial crack deflection angle is second, and the crack shape poses the greatest threat to the safe and stable operation of pot-type insulators.

[0126] Although the above factors have different degrees of influence, they all have a certain impact on the life of pot insulators. Therefore, considering the above factors in the prediction process can improve the accuracy of the prediction to a certain extent. For example, cutting a section corresponding to the stress ratio from the seismic load can reduce the amount of calculation while ensuring the accuracy of the prediction.

[0127] Step 24: When the crack of the pot-type insulator model enters the rapid expansion stage, the time taken for the crack to enter the rapid expansion stage is obtained.

[0128] It should be noted that the operating temperature range of pot insulators is usually wide. Although the specific values ​​may vary depending on the manufacturer and specific model (different manufacturers may use different materials and technologies, which will affect the specific temperature range and performance indicators of pot insulators. For details, please refer to the technical specifications provided by the manufacturer), in general, the operating temperature range of pot insulators will be between -40°C and 90°C to ensure the reliability and performance stability of pot insulators under various environmental conditions; under extreme working conditions, extreme loads are the main driving force for crack propagation, which is far greater than the effect of loads brought by temperature fields on crack propagation. In order to simplify the model and reduce calculations, the effect of temperature can be ignored in the model construction stage, and the temperature field is not added; but temperature has a greater influence on the fracture toughness of the material:

[0129] Take three temperatures of -20℃, 20℃ and 60℃, respectively, and simulate the crack propagation under normal working conditions for the initial model with different types of cracks, and obtain the stress intensity factor curves of different crack types at different temperatures with crack propagation length and the fatigue crack propagation aN curves at different temperatures. For details, please refer to Fig. 22 , Fig.23 , Fig.24 and Fig.25 ;Depend on Fig. 22 , Fig.23 and Fig.24 It can be seen that the changes in the stress intensity factors of the initial model with type I crack at the three temperatures tend to be consistent, all showing an exponential upward trend. The stress intensity factor of the initial model with type III crack is within ±0.005 MPa·m 1 / 2 The fluctuation is relatively stable. The stress intensity factor of the initial model with type II crack has a more obvious fluctuation range than that of type III stress intensity factor. Before the crack expands to 60 μm, the fluctuation of the stress intensity factor of the initial model with type II crack is relatively small. As the crack length increases, the range gradually expands until the stable expansion stage of fatigue crack ends. Fig.25 From the relationship between the crack extension length and crack extension time of the initial model with type I crack set at different temperatures, it can be seen that both low and high temperature environments will accelerate the crack extension rate of the initial model. Compared with the low temperature environment, the high temperature will accelerate the aging of the insulating material of the basin insulator, which has a greater impact on the fatigue crack extension life.

[0130] Therefore, in this step, if the fracture toughness parameters such as stress intensity factor, J integral or crack tip opening displacement are used to judge whether the crack has entered the rapid expansion stage, the critical value of the stress intensity factor, the critical value of the J integral and the critical value of the crack tip opening displacement of the target pot insulator at the temperature of the environment should be selected as the judgment indicators, which can improve the accuracy of the prediction.

[0131] Step 25: predict the failure time of the target pot-type insulator under extreme working conditions according to the duration.

[0132] See also Fig.26 , a third embodiment of the present invention provides a system for predicting failure time of a pot-type insulator under extreme working conditions, comprising:

[0133] A model building module 301 is used to build a pot-type insulator model according to the characteristics of the target pot-type insulator and the corresponding extreme load;

[0134] A crack extension simulation module 302 is used to set cracks on the pot-type insulator model and perform crack extension simulation;

[0135] The data acquisition module 303 is used to acquire the time taken for the crack to enter the rapid expansion stage when the crack of the pot-type insulator model enters the rapid expansion stage;

[0136] The prediction module 304 is used to predict the failure time of the target pot insulator under extreme working conditions according to the duration.

[0137] Embodiment 4 of the present invention provides a device for predicting failure time of a pot-type insulator under extreme working conditions, including a processor and a memory;

[0138] A memory, used for storing program codes and transmitting the program codes to a processor;

[0139] A processor is used to execute the method for predicting the failure time of a pot-type insulator under extreme working conditions as described in any one of the above items according to the instructions in the program code.

[0140] Embodiment 5 of the present invention provides a storage medium, which is used to store program codes, and the program codes are used to execute the method for predicting the failure time of pot-type insulators under extreme working conditions described in any one of the above items.

[0141] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0142] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0143] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0144] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0145] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0146] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for predicting the failure time of a pot-type insulator under extreme working conditions, characterized in that: include: According to the characteristics of the target pot insulator and the corresponding extreme loads, a pot insulator model is constructed; Set cracks on the pot insulator model and perform crack propagation simulation; When the crack enters the rapid expansion stage, obtaining the time taken for the crack to enter the rapid expansion stage; The failure time of the target pot-type insulator under extreme working conditions is predicted according to the duration.

2. The method for predicting failure time of pot-type insulators under extreme working conditions according to claim 1 is characterized in that: The step of constructing a pot-type insulator model according to the characteristics of the target pot-type insulator and the corresponding extreme loads specifically includes: According to the characteristics of the target pot insulator, an initial model is constructed; An extreme load is applied to the initial model to obtain a pot-type insulator model.

3. The method for predicting failure time of pot-type insulators under extreme working conditions according to claim 1, characterized in that: The extreme loads include earthquake loads; If the earthquake does not occur, the method further comprises: According to the corresponding site characteristics of the target pot-type insulator, the design response spectrum is obtained; The design response spectrum is adopted and combined with the response spectrum analysis method to calculate the response acceleration spectrum; The response acceleration spectrum is convolved with the structural characteristics of the target pot-type insulator to calculate the seismic load of the target pot-type insulator.

4. The method for predicting failure time of pot-type insulators under extreme working conditions according to claim 3 is characterized in that: After convolving the response acceleration spectrum with the structural characteristics of the target pot-type insulator and calculating the seismic load of the target pot-type insulator, the method further includes: According to the stress ratio of the target pot-type insulator, a section corresponding to the stress ratio is cut from the seismic load to update the seismic load.

5. The method for predicting failure time of pot-type insulators under extreme working conditions according to claim 1, characterized in that: The extreme loads include earthquake loads; If an earthquake has occurred, the method further comprises: Obtain the actual acceleration time history data of the earthquake that has occurred; The actual acceleration time history data is convolved with the structural characteristics of the target pot-type insulator to calculate the seismic load of the target pot-type insulator.

6. The method for predicting failure time of pot-type insulators under extreme working conditions according to claim 1, characterized in that: The extreme load includes a typhoon load; and the method further includes: The wind speed spectrum is calculated using the Davenport wind speed spectrum formula using typhoon data and the corresponding site characteristics of the target pot insulator. The wind speed spectrum is used to simulate the pulsating wind speed time history through the harmonic synthesis method; According to the air density, pulsating wind speed time history and the wind characteristics of the target pot insulator, the instantaneous wind load of the target pot insulator under the corresponding typhoon level is calculated.

7. The method for predicting failure time of pot-type insulators under extreme working conditions according to claim 6, characterized in that: After calculating the instantaneous wind load of the target pot-type insulator under the corresponding typhoon level according to the air density, the pulsating wind speed time history and the wind-receiving characteristics of the target pot-type insulator, the method further includes: According to the stress ratio of the target pot insulator, a section corresponding to the stress ratio is cut from the instantaneous wind load as the typhoon load.

8. A failure time prediction system for pot-type insulators under extreme working conditions, characterized in that: include: A model building module is used to build a pot insulator model according to the characteristics of the target pot insulator and the corresponding extreme loads; Crack propagation simulation module, used to set cracks on the pot insulator model and perform crack propagation simulation; A data acquisition module, used for acquiring the time taken for the crack to enter the rapid expansion stage when the crack of the pot-type insulator model enters the rapid expansion stage; A prediction module is used to predict the failure time of the target pot-type insulator under extreme working conditions according to the duration.

9. A device for predicting the failure time of a pot-type insulator under extreme working conditions, characterized in that: including a processor and a memory; The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the method for predicting the failure time of a pot-type insulator under extreme working conditions according to the instructions in the program code.

10. A storage medium, characterized in that: The storage medium is used to store program codes, and the program codes are used to execute the method for predicting failure time of pot-type insulators under extreme working conditions as described in any one of claims 1 to 7.

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