CN-116682241-B - Disc-type suspension porcelain insulator porcelain piece rupture early warning system and method in extremely cold environment

CN116682241BCN 116682241 BCN116682241 BCN 116682241BCN-116682241-B

Abstract

The invention provides a disc-type suspension porcelain insulator porcelain piece rupture early warning system and method in an extremely cold environment, and relates to the field of degradation monitoring of high-voltage equipment. The remote early warning system is used for receiving the stress and temperature data, judging whether the cement adhesive part loses stability or not based on the stress data, calculating the total amount of opening displacement of the tip of the downward development of the instability crack based on the temperature data, judging whether the total amount of opening displacement of the tip of the downward development of the instability crack exceeds a critical value and giving an alarm. According to the invention, the real-time change of frost heaving force is obtained through monitoring the temperature, so that the insulator porcelain is subjected to fracture early warning, the insulator fault can be more accurately early warned, and the false alarm rate are reduced.

Inventors

LI BO
WANG SHENGHUI
WANG XIURU
MAI JIAMIN
LI ZHONGWEI
SHANG XIN
ZHANG XINWEI
AN YIYAN
WANG BO
LIU TIANQI
WANG KUNHAN
LIANG JIAYU
DAI YUWEI

Assignees

国网内蒙古东部电力有限公司电力科学研究院
华北电力大学
国家电网有限公司

Dates

Publication Date: 20260508
Application Date: 20230517

Claims (8)

1. The utility model provides a disk suspension porcelain insulator porcelain piece early warning system that breaks in extremely cold environment which characterized in that, including stress temperature acquisition system and remote early warning system, wherein: The stress temperature acquisition system is used for acquiring stress and temperature data at two bonding interface positions of the porcelain part of the porcelain insulator and the cement adhesive in real time and transmitting the stress and temperature data to the remote early warning system; the remote early warning system is used for receiving stress and temperature data, judging whether the cement adhesive part loses stability based on the stress data, calculating the total amount of opening displacement of the downward-developed tip of the unstable crack based on the temperature data, judging whether the total amount of opening displacement of the downward-developed tip of the unstable crack exceeds a critical value, and sending an alarm if the total amount of opening displacement exceeds the critical value; The stress temperature acquisition system comprises a first stress temperature sensor and a second stress temperature sensor, wherein the first stress temperature sensor is arranged at a stress concentration position of a porcelain part of the disc-type suspension porcelain insulator, namely at a starting position of an opening end of a downward development of a instability crack; The remote early warning system is also used for: based on the temperature data and a derived heat transfer characteristic calculation formula in the process of icing the moisture in the insulator, calculating the real-time temperature T at the tip of the downward development of the unstable crack; Calculating uniform stress P and linear distribution stress K at the tip of the downward development of the destabilizing crack based on real-time temperature T at the tip of the downward development of the destabilizing crack, and calculating linear distribution frost heaving stress difference delta K T caused by temperature difference from the opening of the downward development of the destabilizing crack to the tip of the downward development of the destabilizing crack; Calculating a first stress intensity factor F ′ I based on uniformly distributed stress P at the tip of downward development of the unstable crack, calculating a second stress intensity factor F ″ I based on linear distribution frost heaving stress difference delta K T caused by temperature difference, and obtaining a type I stress intensity factor F I based on the sum of the first stress intensity factor F ′ I and the second stress intensity factor F ″ I ; Calculating the expansion displacement gamma e generated in the elastic stage at the downward-developed tip of the instability crack based on the I-type stress intensity factor F I , and calculating the expansion displacement gamma P generated in the plastic stage at the downward-developed tip of the instability crack based on the thickness of the porcelain part of the in-service disc-type suspension porcelain insulator; Based on the sum of the expansion displacement gamma e generated in the elastic stage and the expansion displacement gamma P generated in the plastic stage, the total amount gamma of the expansion displacement at the downward development tip of the unstable crack at the current ambient temperature is obtained.
2. The disc-type suspension porcelain insulator porcelain piece rupture early warning system in an extremely cold environment according to claim 1, wherein the remote early warning system is further used for calculating stress strength sigma born by the disc-type suspension porcelain insulator in service in real time according to an area A of a pre-buried strain gauge of a first stress temperature sensor or a second stress temperature sensor and a fracture strength formula, comparing the stress strength sigma with porcelain piece theoretical fracture strength sigma th , and when sigma is larger than or equal to sigma th , showing that after a cement adhesive part of the disc-type suspension porcelain insulator in service undergoes repeated freeze thawing cycles, the stress generated on the porcelain piece due to volume change exceeds a critical value that intrinsic cracks of the porcelain piece do not continue to develop downwards, and the cement adhesive part loses stability.
3. The disc-type suspension porcelain insulator porcelain piece rupture early warning system in an extremely cold environment according to claim 2, wherein the rupture strength formula 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-buried strain gauge, and sigma represents the stress intensity born by the in-service disc type suspension porcelain insulator in real time.
4. The disc-type suspension porcelain insulator porcelain piece rupture early warning system in an extremely cold environment according to claim 2, wherein the remote early warning system is further used for calculating a porcelain piece theoretical breaking strength sigma th based on a crack instability formula, and the crack instability formula is as follows: wherein E represents the elastic modulus of the porcelain; Representing the surface energy of the porcelain and a representing the lattice constant of the porcelain.
5. The disc-type suspension porcelain insulator porcelain piece rupture early warning system in an extremely cold environment according to claim 1, wherein the heat transfer characteristic calculation formula is as follows: Wherein T i represents the real-time temperature of a certain position in the destabilizing crack, T 1 represents the temperature of the starting position of the opening end of the destabilizing crack which is downwards developed, T 2 represents the real-time temperature of the other end of the porcelain piece in the shortest growth direction of the destabilizing crack which is downwards developed, H represents the thickness of the porcelain piece part of the in-service disc type suspension porcelain insulator, and x represents the distance from the starting position of the opening end of the destabilizing crack which is downwards developed in the length direction of the destabilizing crack, and x is more than or equal to 0 and less than or equal to H.
6. The disc-type suspension porcelain insulator porcelain piece rupture early warning system in an extremely cold environment according to claim 5, wherein the calculation formula of the uniform stress P at the downward-developed tip of the unstable crack is as follows: wherein T represents the real-time temperature at the tip of the downward development of the destabilizing crack, E (T) represents the elastic modulus of ice at temperature T; the calculation formula of the linear distribution stress K at the downward-developed tip of the destabilizing crack is as follows: Where DeltaT represents the temperature increase at a location within the destabilizing crack during heat transfer, ,0≤x≤H。
7. The disc-type suspension porcelain insulator porcelain piece rupture early warning system in an extremely cold environment according to claim 5, wherein the calculation formulas of the first stress intensity factor F ′ I and the second stress intensity factor F ″ I are respectively: The calculation formula of the opening displacement gamma e generated by the downward-developed tip of the destabilizing crack in the elastic stage is as follows: Wherein mu is Poisson's ratio of the raw material of the porcelain piece, E is elastic modulus of the raw material of the porcelain piece, sigma s is uniform tensile stress of a plastic region of the crack surface of the porcelain piece, and F I is an I-type stress intensity factor; The calculation formula of the opening displacement gamma P generated at the plastic stage of the downward-developed tip of the destabilizing crack is as follows: Wherein r P is a rotation factor, 0.3-0.5 is taken, V P is the displacement of the plastic part extensometer, h represents the residual deformation of the material at the yield limit, and h=0.2%H.
8. A disc-type suspension porcelain insulator porcelain piece rupture early warning method in an extremely cold environment is characterized by comprising the following steps: S1, a stress temperature acquisition system acquires stress and temperature data at two bonding interface positions of a porcelain part of a porcelain insulator and cement adhesive in real time, and sends the stress and temperature data to a remote early warning system; step S2, the remote early warning system receives stress data and judges whether the cement adhesive part loses stability based on the stress data: Step S201, calculating the stress intensity sigma born by the in-service disc type suspension porcelain insulator in real time according to the area A of the pre-buried strain gauge and a fracture intensity formula; step S202, calculating theoretical breaking strength sigma th of the porcelain piece based on a crack instability formula; Step S203, comparing the stress intensity sigma with the theoretical breaking intensity sigma th of the porcelain piece, and when the sigma is more than or equal to sigma th , indicating that the cement adhesive part loses stability; Step S3, the remote early warning system receives the temperature data, calculates the total amount of opening displacement of the downward-developed tip of the unstable crack based on the temperature data, judges whether the total amount of opening displacement of the downward-developed tip of the unstable crack exceeds a critical value, and if the total amount of opening displacement exceeds the critical value, gives an alarm: Step 301, the remote early warning system calculates the real-time temperature T at the tip of the downward development of the unstable crack based on the temperature data and a derived calculation formula of the heat transfer characteristic in the process of freezing the moisture in the insulator; Step S302, calculating uniform stress P and linear distribution stress K at the tip of the downward development of the unstable crack based on real-time temperature T at the tip of the downward development of the unstable crack, and calculating linear distribution frost heaving stress difference delta K T caused by temperature difference from the opening of the downward development of the unstable crack to the tip of the downward development of the unstable crack; Step S303, calculating a first stress intensity factor F ′ I based on uniformly distributed stress P at the tip of the downward development of the unstable crack, calculating a second stress intensity factor F ″ I based on linear distribution frost heaving stress difference delta K T caused by temperature difference, and obtaining an I-type stress intensity factor F I based on the sum of the first stress intensity factor F ′ I and the second stress intensity factor F ″ I ; step S304, calculating the expansion displacement gamma e generated in the elastic stage at the downward-developed tip of the instability crack based on the I-type stress intensity factor F I , and calculating the expansion displacement gamma P generated in the plastic stage at the downward-developed tip of the instability crack based on the thickness of the ceramic part of the in-service disc-type suspension ceramic insulator; Step S305, obtaining the total amount gamma of the expansion displacement of the downward development tip of the unstable crack at the current ambient temperature based on the sum of the expansion displacement gamma e generated in the elastic stage and the expansion displacement gamma P generated in the plastic stage; step S306, judging whether the total amount gamma of opening displacement of the downward-developed tip of the unstable crack exceeds a critical value, and if so, sending out an alarm.

Description

Disc-type suspension porcelain insulator porcelain piece rupture early warning system and method in extremely cold environment Technical Field The invention belongs to the technical field of degradation monitoring of high-voltage equipment, and particularly relates to a disc-type suspension porcelain insulator porcelain piece rupture early warning system and method in an extremely cold environment. Background The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art. The disk-type suspension porcelain insulator has good chemical stability and thermal stability, and good electrical and mechanical properties, has the dual functions of mechanically supporting a conductor and insulating the conductor from a grounding structure, and is widely applied to power transmission lines and substations. However, as the operational life of disc porcelain insulators increases, particularly in severe operating environments such as extremely low temperatures, strong wind and sand, and severe fouling areas, the performance of disc-type suspended porcelain insulators may accelerate degradation. At extremely low temperature, the difference exists in thermal expansion coefficient and cold contraction coefficient of materials such as ice, porcelain, adhesive and the like in the insulator, larger mechanical stress can be generated, and the porcelain piece can be cracked due to stress concentration, so that the zero-value insulator is formed. Furthermore, under the action of overvoltage, high current can flow through the insulator body to cause explosion of the insulator string, once the porcelain insulator bursts and the electric wire falls off, irrecoverable loss is caused, even extremely bad social influence is caused, and the safe and stable operation of a power grid is seriously threatened. Therefore, the research on the early warning system for the partial fracture of the porcelain part of the in-service disc porcelain insulator, which is subjected to multiple freeze thawing cycles in extremely cold environments, is urgent. There are currently two directions for detection and early warning of degraded porcelain insulators. Firstly, by manual detection, the method consumes a large amount of manpower, material resources and financial resources, and is almost impossible under the condition that the number of insulators is rapidly increased in the high-speed development of a power grid, and in addition, the manual detection has great uncertainty and cannot guarantee the accuracy of detection results. Secondly, the detection mode greatly improves the detection efficiency and safety by carrying out remote monitoring detection through electronic equipment such as unmanned aerial vehicle, but is greatly influenced by natural environment factors, the accuracy of a detection result is less in proportion of manual control, and the requirement of ensuring safe operation of a power grid is difficult to completely meet. Disclosure of Invention In order to overcome the defects in the prior art, the invention provides a disc-type suspension porcelain insulator porcelain piece rupture early warning system and method in an extremely cold environment, wherein the real-time change of frost heaving force is obtained through monitoring the temperature, so that the porcelain piece of the insulator is ruptured and early warned, the porcelain piece is ruptured to serve as the premise of the fault of the in-service disc-type porcelain insulator, the natural process is met, the insulator fault can be more accurately early warned, the false alarm and the leakage alarm rate are reduced, and the technical problem that the in-service insulator porcelain piece rupture fault cannot be detected in real time is solved. To achieve the above object, one or more embodiments of the present invention provide the following technical solutions: the invention provides a disc-type suspension porcelain insulator porcelain piece rupture early warning system in an extremely cold environment. The utility model provides a disk suspension porcelain insulator porcelain piece early warning system that breaks in extremely cold environment, includes stress temperature acquisition system and remote early warning system, wherein: The stress temperature acquisition system is used for acquiring stress and temperature data at two bonding interface positions of the porcelain part of the porcelain insulator and the cement adhesive in real time and transmitting the stress and temperature data to the remote early warning system; And the remote early warning system is used for receiving the stress and temperature data, judging whether the cement adhesive part loses stability based on the stress data, simultaneously calculating the total amount of opening displacement of the downward-developed tip of the unstable crack based on the temperature data, judging whether the total amount of opening displace