Research On The Long-term Reliability Of Flexible High-voltage Cable Terminals Under Bending Conditions

With the rapid development of the national economy and the accelerating pace of urbanization,the use of power cables in the power grid is becoming more and more widespread.To ensure the safe and reliable operation of power cables,it has become an important task for power supply companies.The prefabricated flexible cable terminal is widely used in the cable terminal,but the failure of the prefabricated flexible terminal accounts for a high proportion of failures of the cable attachment,and the faulty terminals generally have different bending degrees of operation.The bending has a great influence on the safe and stable operation of the cable terminal.It is necessary to study the performance testing equipment and the evaluation method under the bent state of the cable terminal.At present,in the field of prefabricated flexible cable terminal detection,there is a lack of methods and techniques for detecting bending conditions,and equipment for on-line monitoring of interface stress has not yet been formed.Therefore,related research needs to be carried out.This thesis deeply analyzes the influence of bending on the operating characteristics of the prefabricated flexible cable terminal,introduces the contact interface characteristics between the cable termination and the cable,and studies the common methods for detecting stress and strain in the current engineering field.The FBG sensing technology was applied to the field of interface stress and bending state detection of flexible cable terminals.The fiber grating sensor measurement theory that was applied in the cable terminal interface stress detection was analyzed,and the calibration experiment was performed at the same time;the wavelength of the fiber grating sensor was obtained.Correspondences between stresses,and further establish the wavelength as a function of bending position and bending angle.At the same time,the influences of interface stress characteristics,breakdown voltage,and partial discharge of the cable termination were also studied.The time-temperature equivalence principle was used to determine the elongation of the inner surface of the cable at the time of bending,and different bending degrees were determined.Cable terminal life.Completed the development of the cable terminal interface stress detection host,completed the study of the relationship between the wavelength and the interface stress of the FBG fiber grating,realized the interface stress measurement using the fiber grating to the cable terminal,and completed the demonstration software development,which can be used to understand the cable terminal bending operation through the computer.And can intuitively display the corresponding interface stress and operating conditions,real-time monitoring of cable terminal bending operation of the early warning function.The successful application of the research results in the actual project,through the detection of inter facial stress can predict the cable terminal's safe operating life and storage life,at the same time,provide a strong support for safe operation under the cable terminal bending conditions.