Disclosed are a porcelain piece breakage early warning system and method for disc-type suspension porcelain insulators in an extremely cold environment.

Abstract

The application provides a porcelain piece breakage early warning system and method for disc-type suspension porcelain insulators in extremely cold environments, and relates to the field of high-voltage equipment degradation monitoring.The system comprises a stress and temperature acquisition system, which is used for acquiring stress and temperature data at two bonding interface positions of a porcelain piece part and a cement adhesive of a porcelain insulator in real time, and sending the stress and temperature data to a remote early warning system; the remote early warning system is used for receiving the stress and temperature data, judging whether the cement adhesive part has lost stability based on the stress data, calculating the total opening displacement of a tip of a downward development unstable crack based on the temperature data, and judging whether the total opening displacement of the tip of the downward development unstable crack exceeds a critical value and issuing an alarm. The application can obtain real-time changes of frost heaving force through temperature monitoring, and further perform breakage early warning on the insulator porcelain piece, so that the insulator fault can be more accurately early warned, and the false alarm and missed alarm rates are reduced.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage equipment deterioration monitoring technology, and particularly relates to a system and method for early warning of porcelain component cracking in disc-type suspension porcelain insulators in extremely cold environments. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Disc-type suspension porcelain insulators possess excellent chemical and thermal stability, as well as good electrical and mechanical properties. They serve the dual function of mechanically supporting the conductor and insulating it from the grounding structure, making them widely used in transmission lines and substations. However, with the increase in the service life of disc-type porcelain insulators, especially in harsh operating environments such as extremely low temperatures, strong winds and sandstorms, and heavily polluted areas, the performance of disc-type suspension porcelain insulators will deteriorate more rapidly.

[0004] At extremely low temperatures, the differences in the coefficients of thermal expansion and contraction of materials such as ice, porcelain, and adhesives inside insulators can generate significant mechanical stress. Stress concentration can lead to cracking of the porcelain components, resulting in a zero-value insulator. Furthermore, under overvoltage conditions, a large current can flow through the insulator body, causing the insulator string to explode. Once the porcelain insulator bursts and the wire detaches, it will cause irreparable damage and even extremely serious social consequences, severely threatening the safe and stable operation of the power grid. Therefore, research on early warning systems for partial cracking of in-service disc-type porcelain insulator components in extremely cold environments that have undergone multiple freeze-thaw cycles is urgently needed.

[0005] Currently, there are two approaches to the detection and early warning of deteriorated porcelain insulators. One is manual inspection, which is not only extremely resource-intensive but also virtually impossible given the rapid development of the power grid and the surge in the number of insulators; furthermore, manual inspection is inherently uncertain and cannot guarantee the accuracy of the results. The second approach involves remote monitoring and inspection using electronic devices such as drones. This method significantly improves efficiency and safety, but it is heavily influenced by natural environmental factors, and the accuracy of the results is subject to less human control, making it difficult to fully meet the requirements for ensuring the safe operation of the power grid. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention provides a system and method for early warning of porcelain component cracking in disc-type suspension porcelain insulators in extremely cold environments. By monitoring the temperature to obtain real-time changes in frost heave force, the system can provide early warning of porcelain component cracking. Using porcelain component cracking as a prerequisite for faults in in-service disc-type porcelain insulators is consistent with natural processes, enabling more accurate early warning of insulator faults, reducing false alarms and missed alarms, and solving the technical problem of not being able to detect porcelain component cracking faults in in-service insulators in real time.

[0007] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0008] The first aspect of this invention provides an early warning system for the cracking of porcelain components in disc-type suspension porcelain insulators in extremely cold environments.

[0009] A crack prevention system for disc-type suspension porcelain insulators in extremely cold environments includes a stress-temperature acquisition system and a remote early warning system, wherein:

[0010] The stress and temperature acquisition system is used to acquire stress and temperature data at the two bonding interfaces between the porcelain part and the cement adhesive of the porcelain insulator in real time, and send the stress and temperature data to the remote early warning system.

[0011] The remote early warning system receives stress and temperature data. Based on the stress data, it determines whether the cement adhesive has lost stability. At the same time, based on the temperature data, it calculates the total opening displacement at the tip of the unstable crack and determines whether the total opening displacement at the tip of the unstable crack exceeds a critical value. If it exceeds the critical value, an alarm is issued.

[0012] The second aspect of this invention provides a method for early warning of cracking of porcelain components in disc-type suspension porcelain insulators in extremely cold environments.

[0013] A method for early warning of porcelain component cracking in disc-type suspension porcelain insulators in extremely cold environments includes the following steps:

[0014] Step S1: The stress and temperature acquisition system acquires stress and temperature data at the two bonding interfaces between the porcelain part of the porcelain insulator and the cement adhesive in real time, and sends the stress and temperature data to the remote early warning system.

[0015] Step S2: The remote early warning system receives stress data and, based on the stress data, determines whether the cement adhesive component has lost stability.

[0016] Step S201: Calculate the stress intensity σ that the in-service disc-type suspension porcelain insulator bears in real time, based on the area A of the pre-embedded strain gauge and the fracture strength formula.

[0017] Step S202: Calculate the theoretical fracture strength σ of the ceramic part based on the crack instability formula. th ;

[0018] Step S203: Compare the stress intensity σ with the theoretical fracture strength σ of the ceramic part th In comparison, when σ≥σ th When this occurs, it indicates that the cementitious adhesive has partially lost its stability;

[0019] Step S3: The remote early warning system receives temperature data, calculates the total opening displacement at the tip of the downward-propagating unstable crack based on the temperature data, and determines whether the total opening displacement at the tip of the downward-propagating unstable crack exceeds a critical value. If it exceeds the critical value, an alarm is issued.

[0020] Step S301: Based on temperature data and the derived formula for calculating the heat transfer characteristics during the freezing of moisture inside the insulator, the remote early warning system calculates the real-time temperature T at the tip of the downward propagation of the unstable crack.

[0021] Step S302: Based on the real-time temperature T at the tip of the downward propagation of the unstable crack, calculate the uniformly distributed stress P and the linearly distributed stress K at the tip of the downward propagation of the unstable crack, and calculate the linearly distributed frost heave stress difference ΔK caused by the temperature difference between the opening of the downward propagation of the unstable crack and the tip of the unstable crack. T ;

[0022] Step S303: Calculate the first stress intensity factor F′ based on the uniformly distributed stress P at the tip of the downward propagation of the unstable crack. I Based on the linear distribution of frost heave stress difference ΔK caused by temperature difference T Calculate the second stress intensity factor F″ I Based on the first stress intensity factor F′ I Second stress intensity factor F″ I The sum of these yields the Type I stress intensity factor F. I ;

[0023] Step S304: Based on Type I stress intensity factor F I Calculate the opening displacement γ generated at the tip of the downward propagation of the unstable crack in the elastic stage. e Based on the thickness of the porcelain component in an in-service disc-type suspension porcelain insulator, the opening displacement γ generated at the tip of the downward propagation of the unstable crack during the plastic stage is calculated. P ;

[0024] Step S305: Based on the opening displacement γ generated in the elastic stage e The opening displacement γ generated during the plastic stage P The sum of these values ​​yields the total displacement γ at the tip of the downward propagation of the unstable crack under the current ambient temperature.

[0025] Step S306: Determine whether the total opening displacement γ at the tip of the unstable crack propagating downward exceeds the critical value. If it exceeds the critical value, issue an alarm.

[0026] The above one or more technical solutions have the following beneficial effects:

[0027] 1. This invention introduces strain gauges as the core component of the stress-temperature acquisition system in the ceramic component fracture early warning system, which solves the problem of not being able to monitor in real time the stress generated on the ceramic component through the bonding interface by cement adhesive that has undergone certain deformation due to multiple freeze-thaw cycles in extremely cold environments.

[0028] 2. As the temperature in the region decreases, the water inside the material of the disc-type suspension porcelain insulator begins to freeze from the outside in. During the freezing process, the water expands in volume, thus generating additional stress on the intrinsic cracks. As the temperature continues to drop, the water within the intrinsic cracks of the insulator continues to freeze until the entire crack is filled. If the temperature continues to drop after the crack is completely filled with ice, the frost heave force will further increase, making it highly susceptible to the propagation of crack tips in the porcelain components of the insulator, leading to overall failure. This invention takes into account the influence of temperature on frost heave force. As the temperature changes, the frost heave force also changes in real time. Therefore, this invention can provide early warning of insulator component cracking based on the real-time changes in frost heave force through temperature monitoring.

[0029] 3. This invention uses the fracture of the porcelain component as a prerequisite for faults in in-service disc-type porcelain insulators, which conforms to the natural process and can more accurately provide early warning of insulator faults, reducing false alarms and missed alarms.

[0030] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0032] Figure 1 This is a schematic diagram showing the stress concentration location of the ceramic component of the disc-type suspension porcelain insulator of the present invention;

[0033] Figure 2 This is a structural diagram of the sensor of the present invention;

[0034] Figure 3 This is a diagram illustrating the architecture of a ceramic component crack early warning system according to the first embodiment of the present invention.

[0035] Figure 4 This is a signal transmission flow diagram of the second embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram showing the distribution of frost heave force in the unstable crack of the present invention.

[0037] The components represented by each number in the attached diagram are listed below: 1. Transmission line, 2. Cement adhesive part, 3. Ceramic part, 4. Stress concentration point of ceramic part, 5-1. First sensor, 5-2. Second sensor, 6. Signal transmitter, 7. Satellite terminal, 8. Signal receiver, 9. Main unit. Detailed Implementation

[0038] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0039] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0040] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0041] The overall concept proposed in this invention is as follows:

[0042] Reference for Disc-type Suspension Porcelain Insulators and Crack Structures Figure 1 As shown, the disc-type porcelain insulator on transmission line 1 consists of a cement adhesive component 2, a porcelain component 3, and other parts. Based on existing theories and extensive experimental simulations, it is known that when an in-service disc-type suspension porcelain insulator undergoes multiple freeze-thaw cycles in an extremely cold environment, the moisture inside the cracks will exert stress on the porcelain component due to freeze-thaw expansion and other effects during the freezing process. Figure 1 The part shown in Figure 4 is the stress concentration point of the porcelain component, which is also the part where the porcelain component most often begins to crack. When cracks are generated here and expand to a certain extent, the porcelain component will crack, causing overall damage to the insulator and seriously threatening the safe operation of transmission lines and power systems.

[0043] It is crucial and urgent to implement early warning of the risk of cracking of the porcelain components of in-service disc-type suspension porcelain insulators in extremely cold environments through monitoring methods. To this end, this invention provides an early warning method for the cracking of porcelain components of in-service disc-type suspension porcelain insulators in extremely cold environments, and designs a corresponding real-time early warning system for porcelain component cracking for implementation.

[0044] In general, the technical solution of the present invention includes:

[0045] The remote early warning system can acquire in real time the stress G generated on the porcelain part through the bonding interface of the cement adhesive part of the in-service disc-type suspension porcelain insulator due to volume change after multiple freeze-thaw cycles.

[0046] Based on the area A of the pre-embedded strain gauge and the fracture strength formula, the stress intensity σ that the in-service disc-type suspension porcelain insulator bears in real time is calculated.

[0047] Based on the derived crack instability formula, the above stress intensity σ is compared with the calculated theoretical fracture strength σ of the ceramic part. th In comparison, when σ≥σ th When the stress on the porcelain component exceeds the critical value at which the intrinsic crack in the porcelain component will not continue to propagate downwards due to the change in volume caused by the cement adhesive in the in-service disc-type suspension porcelain insulator after multiple freeze-thaw cycles, the steady-state equilibrium of the intrinsic crack is broken, and the crack gains enough energy to propagate downwards and loses its stability.

[0048] By collecting internal temperature data of disc-type suspension porcelain insulators and deriving the calculation formula for heat transfer characteristics during the freezing of moisture inside the insulators, the real-time temperature T at the tip of the downward propagation of the unstable crack was calculated.

[0049] The stresses within an unstable crack are divided into two categories: one is the uniformly distributed stress, denoted by P, which is equal at all locations within the crack and equal to the stress at the crack's tip during its downward propagation; the other is the linear stress, denoted by K, which varies with temperature differences during heat transfer, and is called linear stress. The difference in linearly distributed stress caused by temperature differences from the crack's initiation point to its tip is denoted by ΔK. T ;

[0050] At the tip of the downward-propagating unstable crack, the frost heave force of the moisture inside the disc-type suspension porcelain insulator after multiple freeze-thaw cycles can cause the already unstable crack to continue to propagate. This effect is caused by the difference ΔK between the uniformly distributed stress P and the linearly distributed stress at the tip of the downward-propagating unstable crack. T Together they were produced;

[0051] Calculate the first stress intensity factor F′ based on the uniformly distributed stress P at the tip of the downward propagation of the unstable crack. I Based on the linear stress difference ΔK at the tip of the downward propagation of the unstable crack. T Calculate the second stress intensity factor F″ I ;

[0052] According to the type I stress intensity factor F I Calculate the opening displacement γ generated when the tip of the unstable crack is in the elastic stage during downward propagation. e Furthermore, considering the opening displacement γ generated when the tip of the unstable crack is in the plastic stage during its downward propagation... P We obtain the total displacement γ at the tip of the downward propagation of the unstable crack under the current ambient temperature.

[0053] Compare the total opening displacement γ at the downward propagation tip of the unstable crack with the critical opening displacement γ at the crack tip. crWhen γ≥γ cr When this occurs, it indicates that the porcelain component of the disc-type suspension porcelain insulator is at risk of breaking and collapsing under the action of frost heave after undergoing multiple freeze-thaw cycles, and an alarm is issued at this time.

[0054] Example 1

[0055] This embodiment discloses an early warning system for the cracking of porcelain components in disc-type suspension porcelain insulators in extremely cold environments.

[0056] like Figure 3 As shown, the disc-type suspension porcelain insulator porcelain component crack early warning system in extremely cold environments includes a stress temperature acquisition system and a remote early warning system, wherein:

[0057] The stress and temperature acquisition system is used to acquire stress and temperature data at the two bonding interfaces between the porcelain part and the cement adhesive of the porcelain insulator in real time, and send the stress and temperature data to the remote early warning system.

[0058] The remote early warning system receives stress and temperature data. Based on the stress data, it determines whether the cement adhesive has lost stability. At the same time, based on the temperature data, it calculates the total opening displacement at the tip of the unstable crack and determines whether the total opening displacement at the tip of the unstable crack exceeds a critical value. If it exceeds the critical value, an alarm is issued.

[0059] In this embodiment, the extreme cold environment is an environment with a temperature below -50 degrees Celsius.

[0060] 1) Stress and Temperature Acquisition System

[0061] The stress-temperature acquisition system includes a first stress-temperature sensor and a second stress-temperature sensor. The first stress-temperature sensor is installed at the stress concentration point of the ceramic part of the disc-type suspension porcelain insulator, that is, at the starting position of the downward propagation opening of the unstable crack. The second stress-temperature sensor is installed at the shortest distance along the downward propagation direction of the unstable crack.

[0062] In this embodiment, the stress temperature acquisition system is powered by a lead wire pre-embedded inside the insulator.

[0063] refer to Figure 2 As shown, the stress-temperature acquisition system includes a first sensor 5-1 and a second sensor 5-2. The first sensor is installed at the bonding interface between the stress concentration point of the ceramic part and the cement adhesive, and the second sensor 5-2 is installed at the point where the crack propagation path is shortest, that is, at the bonding interface between the ceramic part and the cement adhesive on the other side; the thickness of the ceramic part is H.

[0064] The stress-temperature acquisition system is used to acquire the temperature of the two bonding interfaces between the ceramic part and the cement adhesive in real time, as well as the stress generated by the cement adhesive on the ceramic part through the bonding interface, and transmits the data to the remote early warning system through the remote communication system.

[0065] II) Remote Communication System

[0066] In this embodiment, the disc-type suspension porcelain insulator porcelain component cracking early warning system in extremely cold environments also includes a remote communication system. The stress temperature acquisition system and the remote early warning system are connected through the remote communication system. More specifically, the remote communication system is a 5G communication system.

[0067] refer to Figure 3 As shown, the real-time data monitored by the stress-temperature sensor is transmitted to the 5G signal transmitter 6. The 5G signal transmitter 6 transmits the received stress-temperature data to the satellite terminal 7 in the form of a 5G signal, and the satellite terminal 7 transmits it to the remote 5G signal receiver 8. The 5G signal is then fed back to the computer host 9 in a timely manner. The host 9 then converts the 5G signal into the corresponding stress-temperature signal and inputs it into the program for calculation, thereby realizing the real-time monitoring and transmission of remote data.

[0068] III) Remote Early Warning System

[0069] The remote early warning system is used to calculate the total opening displacement γ at the downward propagation tip of the unstable crack based on the real-time temperature at two locations on the bonding interface of the ceramic piece, and to compare the total opening displacement γ at the downward propagation tip of the unstable crack with the critical opening displacement value γ. cr When γ≥γ cr When this occurs, it indicates that the porcelain components of the in-service disc-type suspension porcelain insulator are at risk of fracture after multiple freeze-thaw cycles, and an alarm is issued at this time.

[0070] The remote early warning system calculates the total displacement γ at the tip of the unstable crack through the data processing module in the host 9, and then judges it through the early warning module. The judgment result is displayed on the monitor. When it is judged that there is a risk of cracking in the ceramic piece, the alarm system will be triggered, the warning light will light up or the alarm sound will be emitted, and the alarm window will pop up on the monitor.

[0071] The remote early warning system is also used to calculate the real-time stress intensity σ borne by the in-service disc-type suspension porcelain insulator based on the area A of the pre-embedded strain gauge and the fracture strength formula; and to compare the stress intensity σ with the theoretical fracture strength σ of the porcelain component. th In comparison, when σ≥σ th This indicates that after multiple freeze-thaw cycles, the cement adhesive portion of the in-service disc-type suspension porcelain insulator experiences a change in volume, causing stress on the porcelain component that exceeds the critical value at which intrinsic cracks in the porcelain component will not continue to propagate downwards, resulting in the cement adhesive portion losing its stability.

[0072] Furthermore, the fracture strength formula is as follows:

[0073]

[0074] In the formula, G represents the stress generated on the porcelain part by the cement adhesive part of the in-service disc-type suspension porcelain insulator through the bonding interface; A represents the area of ​​the pre-embedded strain gauge; and σ represents the stress intensity that the in-service disc-type suspension porcelain insulator bears in real time.

[0075] Furthermore, the remote early warning system is also used to calculate the theoretical fracture strength σ of the ceramic component based on the crack instability formula. th The crack instability formula is as follows:

[0076]

[0077] In the formula, E represents the elastic modulus of the ceramic component; α s α represents the surface energy of the ceramic component; α represents the lattice constant of the ceramic component.

[0078] Furthermore, the remote early warning system is also used for:

[0079] Based on temperature data and the derived formula for calculating the heat transfer characteristics during the freezing of moisture inside the insulator, the real-time temperature T at the tip of the downward propagation of the unstable crack is calculated.

[0080] Based on the real-time temperature T at the tip of the downward propagation of the unstable crack, the uniformly distributed stress P and the linearly distributed stress K at the tip of the downward propagation of the unstable crack are calculated. The linearly distributed frost heave stress difference ΔK caused by the temperature difference between the opening of the downward propagation of the unstable crack and the tip of the crack is also calculated. T ;

[0081] Calculate the first stress intensity factor F′ based on the uniformly distributed stress P at the tip of the downward propagation of the unstable crack. I Based on the linear distribution of frost heave stress difference ΔK caused by temperature difference T Calculate the second stress intensity factor F″ I Based on the first stress intensity factor F′ I Second stress intensity factor F″ I The sum of these yields the Type I stress intensity factor F. I ;

[0082] Based on Type I stress intensity factor F I Calculate the opening displacement γ generated at the tip of the downward propagation of the unstable crack in the elastic stage. e Based on the thickness of the porcelain component in an in-service disc-type suspension porcelain insulator, the opening displacement γ generated at the tip of the downward propagation of the unstable crack during the plastic stage is calculated. P ;

[0083] Based on the opening displacement γ generated in the elastic stage e The opening displacement γ generated during the plastic stage P The sum of these values ​​yields the total displacement γ at the tip of the unstable crack propagating downwards under the current ambient temperature.

[0084] Furthermore, the formula for calculating the heat transfer characteristics is as follows:

[0085]

[0086] In the formula, T i T1 represents the real-time temperature at a certain location within the unstable crack; T2 represents the temperature at the starting point of the downward propagation of the unstable crack; T3 represents the real-time temperature at the other end of the shortest growth direction of the unstable crack along the ceramic component; H represents the thickness of the ceramic component in the in-service disc-type suspension ceramic insulator; x represents the distance along the length of the unstable crack from the starting point of the downward propagation of the unstable crack, 0≤x≤H.

[0087] Furthermore, the formula for calculating the uniformly distributed stress P at the tip of the downward propagation of the unstable crack is as follows:

[0088]

[0089] In the formula, T represents the real-time temperature at the tip of the unstable crack propagating downwards; E(T) represents the elastic modulus of ice at temperature T; and ε(T) represents the strain of ice at temperature T.

[0090] Furthermore, the formula for calculating the linearly distributed stress K at the tip of the downward propagation of the unstable crack is as follows:

[0091]

[0092] In the formula, ΔT represents the temperature increment at a certain location within the unstable crack during heat transfer.

[0093] Furthermore, the first stress intensity factor F′ I With the second stress intensity factor F″ I The calculation formulas are as follows:

[0094]

[0095]

[0096] Furthermore, the opening displacement γ generated at the tip of the downward propagation of the unstable crack during the elastic stage e The calculation formula is:

[0097]

[0098] In the formula, μ is the Poisson's ratio of the ceramic material; E is the elastic modulus of the ceramic material; σ s The uniform bra stress in the plastic zone of the cracked surface of the ceramic piece; F I It is a type I stress intensity factor;

[0099] Furthermore, the opening displacement γ generated at the tip of the downward propagation of the unstable crack during the plastic stage P The calculation formula is:

[0100]

[0101] In the formula, r P V is the rotation factor, ranging from 0.3 to 0.5; P The displacement of the extensometer is for the plastic part.

[0102] Example 2

[0103] This embodiment discloses a method for early warning of porcelain component cracking in disc-type suspension porcelain insulators in extremely cold environments.

[0104] like Figure 4 As shown, the method for early warning of porcelain component cracking in disc-type suspension porcelain insulators in extremely cold environments includes the following steps:

[0105] Step S1: The stress and temperature acquisition system acquires stress and temperature data at the two bonding interfaces between the porcelain part of the porcelain insulator and the cement adhesive in real time, and sends the stress and temperature data to the remote early warning system.

[0106] Step S2: The remote early warning system receives stress data and, based on the stress data, determines whether the cement adhesive component has lost stability.

[0107] Step S201: Calculate the stress intensity σ that the in-service disc-type suspension porcelain insulator is subjected to in real time, based on the area A of the pre-embedded strain gauge and the fracture strength formula.

[0108] Step S202: Calculate the theoretical fracture strength σ of the ceramic part based on the crack instability formula. th ;

[0109] Step S203: Compare the stress intensity σ with the theoretical fracture strength σ of the ceramic part th In comparison, when σ≥σ th When this occurs, it indicates that the cementitious adhesive has partially lost its stability;

[0110] Step S3: The remote early warning system receives temperature data, calculates the total opening displacement at the tip of the downward-propagating unstable crack based on the temperature data, and determines whether the total opening displacement at the tip of the downward-propagating unstable crack exceeds a critical value. If it exceeds the critical value, an alarm is issued.

[0111] Step S301: Based on temperature data and the derived formula for calculating the heat transfer characteristics during the freezing of moisture inside the insulator, the remote early warning system calculates the real-time temperature T at the tip of the downward propagation of the unstable crack.

[0112] Step S302: Based on the real-time temperature T at the tip of the downward propagation of the unstable crack, calculate the uniformly distributed stress P and the linearly distributed stress K at the tip of the downward propagation of the unstable crack, and calculate the linearly distributed frost heave stress difference ΔK caused by the temperature difference between the opening of the downward propagation of the unstable crack and the tip of the unstable crack. T ;

[0113] Step S303: Calculate the first stress intensity factor F′ based on the uniformly distributed stress P at the tip of the downward propagation of the unstable crack. I Based on the linear distribution of frost heave stress difference ΔK caused by temperature difference T Calculate the second stress intensity factor F″ I Based on the first stress intensity factor F′ I Second stress intensity factor F″ I The sum of these yields the Type I stress intensity factor F. I ;

[0114] Step S304: Based on Type I stress intensity factor F I Calculate the opening displacement γ generated at the tip of the downward propagation of the unstable crack in the elastic stage. e Based on the thickness of the porcelain component in an in-service disc-type suspension porcelain insulator, the opening displacement γ generated at the tip of the downward propagation of the unstable crack during the plastic stage is calculated. P ;

[0115] Step S305: Based on the opening displacement γ generated in the elastic stage e The opening displacement γ generated during the plastic stage P The sum of these values ​​yields the total displacement γ at the tip of the downward propagation of the unstable crack under the current ambient temperature.

[0116] Step S306: Determine whether the total opening displacement γ at the tip of the unstable crack propagating downward exceeds the critical value. If it exceeds the critical value, issue an alarm.

[0117] The following section details the calculation of the total opening displacement γ at the tip of the downward propagation of the unstable crack, including the following steps:

[0118] 1) Using the collected internal temperature data of the disc-type suspension porcelain insulator and the derived formula for calculating the heat transfer characteristics during the freezing process of moisture inside the insulator, the real-time temperature T at the tip of the downward propagation of the unstable crack is calculated; considering the heat transfer process in the ice, this process is simplified to a linear relationship, and the heat transfer characteristic calculation formula is as follows:

[0119]

[0120] In the formula, T i T1 represents the real-time temperature at a certain location within the unstable crack; T2 represents the temperature at the starting point of the downward propagation of the unstable crack; T3 represents the real-time temperature at the other end of the shortest growth direction of the unstable crack along the ceramic component; H represents the thickness of the ceramic component in the in-service disc-type suspension ceramic insulator; x represents the distance along the length of the unstable crack from the starting point of the downward propagation of the unstable crack, 0≤x≤H.

[0121] 2)Reference Figure 5 As shown, the stresses within an unstable crack are divided into two categories: one is the uniformly distributed stress, denoted by P, which is equal at all locations within the crack and equal to the stress at the crack's downward propagation tip; the other is the linear stress, denoted by K, which varies with temperature differences throughout the crack. The difference in linearly distributed stress caused by temperature differences from the crack's initiation point to its downward propagation tip is denoted by ΔK. T ;

[0122] The formula for calculating the uniformly distributed stress P at the tip of a downward-propagating unstable crack is as follows:

[0123]

[0124] In the formula, T represents the real-time temperature at the tip of the unstable crack propagating downwards; E(T) represents the elastic modulus of ice at temperature T; and ε(T) represents the strain of ice at temperature T.

[0125] The formula for calculating the linearly distributed stress K at the tip of the downward propagation of the unstable crack is as follows:

[0126]

[0127] In the formula, ΔT represents the temperature increment at a certain location within the unstable crack during heat transfer.

[0128]

[0129] 3) At the tip of the downward-propagating unstable crack, the frost heave force of the moisture inside the disc-type suspension porcelain insulator after multiple freeze-thaw cycles can cause the already unstable crack to continue to propagate. This effect is caused by the difference ΔK between the uniformly distributed stress P and the linearly distributed stress at the tip of the downward-propagating unstable crack. T Together they were produced;

[0130] The linear distribution of frost heave stress difference ΔK caused by the temperature difference between the opening of the unstable crack and the tip of the crack propagation point. T The calculation is performed as follows: Calculate the linearly distributed frost heave stress at the downward propagation opening end and the tip of the unstable crack according to the aforementioned formula, i.e., calculate the linearly distributed frost heave stress at x = 0 and x = h respectively, and then subtract them to obtain the linearly distributed frost heave stress difference ΔK. T h represents the residual deformation of the material at its yield strength, h = 0.2%H.

[0131] 4) Calculate the first stress intensity factor F′ based on the uniformly distributed stress P at the tip of the downward propagation of the unstable crack. I Based on the linear stress difference ΔK at the tip of the downward propagation of the unstable crack. T Calculate the second stress intensity factor F″ I ;

[0132] Treating the porcelain component of the disc-type suspension porcelain insulator as an elastic-plastic material, the first stress intensity factor F′ is calculated. I When considering the instability crack as an edge crack, we have:

[0133]

[0134] When considering the heat transfer process, the frost heave stress is a linear load, therefore:

[0135]

[0136] According to the first stress intensity factor F′ I Second stress intensity factor F″ I The expression for the Type I stress intensity factor FI at the tip of the downward propagation of the unstable crack is obtained by combining the following:

[0137] F I =F I ′+F I "

[0138] 5) Based on the Type I stress intensity factor F I Calculate the opening displacement γ generated when the tip of the unstable crack is in the elastic stage during downward propagation. e Furthermore, considering the opening displacement γ generated when the tip of the unstable crack is in the plastic stage during its downward propagation... P We obtain the total displacement γ = γ at the tip of the downward propagation of the unstable crack under the current ambient temperature. e +γ P ;

[0139] The formula for calculating the opening displacement γe generated at the tip of the downward propagation of the unstable crack in the elastic stage is as follows:

[0140]

[0141] In the formula, μ is the Poisson's ratio of the ceramic material; E is the elastic modulus of the ceramic material; σ s The uniform bra stress in the plastic zone of the cracked surface of the ceramic piece; F I It is a type I stress intensity factor.

[0142] The downward propagation tip of the unstable crack is located at the opening displacement γ generated during the plastic stage. P The calculation formula is as follows:

[0143]

[0144] In the formula, r P V is the rotation factor, ranging from 0.3 to 0.5; P The displacement of the extensometer is for the plastic part.

[0145] 6) Compare the total opening displacement γ at the tip of the unstable crack propagating downwards with the critical opening displacement γ at the crack tip. cr When γ≥γ cr When γ < γ, it indicates that the porcelain component of the disc-type suspension porcelain insulator is at risk of fracture and collapse under frost heave force after multiple freeze-thaw cycles, and an alarm is issued. cr At this time, the insulator is still in a relatively safe state.

[0146] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0147] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A system for early warning of porcelain component cracking in disc-type suspension porcelain insulators in extremely cold environments, characterized in that, This includes a stress and temperature acquisition system and a remote early warning system, among which: The stress and temperature acquisition system is used to acquire stress and temperature data at the two bonding interfaces between the porcelain part and the cement adhesive of the porcelain insulator in real time, and send the stress and temperature data to the remote early warning system. The remote early warning system is used to receive stress and temperature data. Based on the stress data, it determines whether the cement adhesive has lost stability. At the same time, based on the temperature data, it calculates the total opening displacement at the tip of the unstable crack that is propagating downwards and determines whether the total opening displacement at the tip of the unstable crack that is propagating downwards exceeds the critical value. If it exceeds the critical value, an alarm is issued. The stress-temperature acquisition system includes a first stress-temperature sensor and a second stress-temperature sensor. The first stress-temperature sensor is installed at the stress concentration point of the ceramic part of the disc-type suspension porcelain insulator, that is, at the starting position of the downward propagation opening of the unstable crack. The second stress-temperature sensor is installed at the shortest distance along the downward propagation direction of the unstable crack. The remote early warning system is also used for: Based on temperature data and the derived formula for calculating the heat transfer characteristics during the freezing of moisture inside the insulator, the real-time temperature T at the tip of the downward propagation of the unstable crack is calculated. Based on the real-time temperature T at the tip of the downward propagation of the unstable crack, the uniformly distributed stress P and the linearly distributed stress K at the tip of the downward propagation of the unstable crack are calculated. The linearly distributed frost heave stress difference ΔK caused by the temperature difference between the opening of the downward propagation of the unstable crack and the tip of the crack is also calculated. T ; The first stress intensity factor F is calculated based on the uniformly distributed stress P at the tip of the downward propagation of the unstable crack. ′ I Based on the linear distribution of frost heave stress difference ΔK caused by temperature difference T Calculate the second stress intensity factor F ″ I Based on the first stress intensity factor F ′ I Second stress intensity factor F ″ I The sum of these yields the Type I stress intensity factor F. I ; Based on Type I stress intensity factor F I Calculate the opening displacement γ generated at the tip of the downward propagation of the unstable crack in the elastic stage. e Based on the thickness of the porcelain component in an in-service disc-type suspension porcelain insulator, the opening displacement γ generated at the tip of the downward propagation of the unstable crack during the plastic stage is calculated. P ; Based on the opening displacement γ generated in the elastic stage e The opening displacement γ generated during the plastic stage P The sum of these values ​​yields the total displacement γ at the tip of the unstable crack propagating downwards under the current ambient temperature.

2. The early warning system for cracking of disc-type suspension porcelain insulator components in extremely cold environments as described in claim 1, characterized in that, The remote early warning system is also used to calculate the real-time stress intensity σ borne by the in-service disc-type suspension porcelain insulator based on the area A of the pre-embedded strain gauge of the first or second stress temperature sensor and the fracture strength formula; and to compare the stress intensity σ with the theoretical fracture strength σ of the porcelain component. th In comparison, when σ≥σ th This indicates that after multiple freeze-thaw cycles, the cement adhesive portion of the in-service disc-type suspension porcelain insulator experiences a change in volume, causing stress on the porcelain component that exceeds the critical value at which intrinsic cracks in the porcelain component will not continue to propagate downwards, resulting in the cement adhesive portion losing its stability.

3. The early warning system for cracking of disc-type suspension porcelain insulator components in extremely cold environments as described in claim 2, characterized in that, The formula for fracture strength is as follows: In the formula, G represents the stress generated on the porcelain part by the cement adhesive part of the in-service disc-type suspension porcelain insulator through the bonding interface; A represents the area of ​​the pre-embedded strain gauge; and σ represents the stress intensity that the in-service disc-type suspension porcelain insulator bears in real time.

4. The early warning system for cracking of disc-type suspension porcelain insulator components in extremely cold environments as described in claim 2, characterized in that, The remote early warning system is also used to calculate the theoretical fracture strength σ of the ceramic component based on the crack instability formula. th The crack instability formula is as follows: In the formula, E represents the elastic modulus of the ceramic part; α represents the surface energy of the ceramic component; α represents the lattice constant of the ceramic component.

5. The early warning system for cracking of disc-type suspension porcelain insulator components in extremely cold environments as described in claim 1, characterized in that, The formula for calculating the heat transfer characteristics is as follows: In the formula, T i T1 represents the real-time temperature at a certain location within the unstable crack; T2 represents the temperature at the starting point of the downward propagation of the unstable crack; T3 represents the real-time temperature at the other end of the shortest growth direction of the unstable crack along the ceramic component; H represents the thickness of the ceramic component in the in-service disc-type suspension ceramic insulator; x represents the distance along the length of the unstable crack from the starting point of the downward propagation of the unstable crack, 0≤x≤H.

6. The early warning system for cracking of disc-type suspension porcelain insulator components in extremely cold environments as described in claim 5, characterized in that, The formula for calculating the uniformly distributed stress P at the tip of the downward propagation of the unstable crack is as follows: In the formula, T represents the real-time temperature at the tip of the downward propagation of the unstable crack; E(T) represents the elastic modulus of ice at temperature T; ε(T) represents the strain of ice at temperature T. The formula for calculating the linearly distributed stress K at the tip of the downward propagation of the unstable crack is: In the formula, ΔT represents the temperature increment at a certain location within the unstable crack during heat transfer. , 0≤x≤H.

7. The early warning system for cracking of disc-type suspension porcelain insulator components in extremely cold environments as described in claim 5, characterized in that, First stress intensity factor F ′ I With the second stress intensity factor F ″ I The calculation formulas are as follows: The opening displacement γ at the tip of the downward propagation of the unstable crack occurs during the elastic stage. e The calculation formula is: In the formula, μ is the Poisson's ratio of the ceramic material; E is the elastic modulus of the ceramic material; σ s The uniform bra stress in the plastic zone of the cracked surface of the ceramic piece; F I It is a type I stress intensity factor; The downward propagation tip of the unstable crack is located at the opening displacement γ generated during the plastic stage. P The calculation formula is: In the formula, r P V is the rotation factor, ranging from 0.3 to 0.5; P denoted as extensometer displacement of the plastic portion; h represents the residual deformation of the material at the yield limit, h = 0.2%H.

8. A method for early warning of porcelain component cracking in disc-type suspension porcelain insulators in extremely cold environments, characterized by: Includes the following steps: Step S1: The stress and temperature acquisition system acquires stress and temperature data at the two bonding interfaces between the porcelain part of the porcelain insulator and the cement adhesive in real time, and sends the stress and temperature data to the remote early warning system. Step S2: The remote early warning system receives stress data and, based on the stress data, determines whether the cement adhesive component has lost stability. Step S201: Calculate the stress intensity σ that the in-service disc-type suspension porcelain insulator is subjected to in real time, based on the area A of the pre-embedded strain gauge and the fracture strength formula. Step S202: Calculate the theoretical fracture strength σ of the ceramic part based on the crack instability formula. th ; Step S203: Compare the stress intensity σ with the theoretical fracture strength σ of the ceramic part th In comparison, when σ≥σ th When this occurs, it indicates that the cementitious adhesive has partially lost its stability; Step S3: The remote early warning system receives temperature data, calculates the total opening displacement at the tip of the downward-propagating unstable crack based on the temperature data, and determines whether the total opening displacement at the tip of the downward-propagating unstable crack exceeds a critical value. If it exceeds the critical value, an alarm is issued. Step S301: Based on temperature data and the derived formula for calculating the heat transfer characteristics during the freezing of moisture inside the insulator, the remote early warning system calculates the real-time temperature T at the tip of the downward propagation of the unstable crack. Step S302: Based on the real-time temperature T at the tip of the downward propagation of the unstable crack, calculate the uniformly distributed stress P and the linearly distributed stress K at the tip of the downward propagation of the unstable crack, and calculate the linearly distributed frost heave stress difference ΔK caused by the temperature difference between the opening of the downward propagation of the unstable crack and the tip of the unstable crack. T ; Step S303: Calculate the first stress intensity factor F based on the uniformly distributed stress P at the tip of the downward propagation of the unstable crack. ′ I Based on the linear distribution of frost heave stress difference ΔK caused by temperature difference T Calculate the second stress intensity factor F ″ I Based on the first stress intensity factor F ′ I Second stress intensity factor F ″ I The sum of these yields the Type I stress intensity factor F. I ; Step S304: Based on Type I stress intensity factor F I Calculate the opening displacement γ generated at the tip of the downward propagation of the unstable crack in the elastic stage. e Based on the thickness of the porcelain component in an in-service disc-type suspension porcelain insulator, the opening displacement γ generated at the tip of the downward propagation of the unstable crack during the plastic stage is calculated. P ; Step S305: Based on the opening displacement γ generated in the elastic stage e The opening displacement γ generated during the plastic stage P The sum of these values ​​yields the total displacement γ at the tip of the downward propagation of the unstable crack under the current ambient temperature. Step S306: Determine whether the total opening displacement γ at the tip of the unstable crack propagating downward exceeds the critical value. If it exceeds the critical value, issue an alarm.

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