Diagnosis Method of Decay-like Composite Insulators in a High-Humidity Environment Based on Characteristic Coefficient of Temperature Rise Gradient

Abstract

At present, the temperature rise in insulators is observed using infrared thermometry as a common method of diagnosing decay-like insulators. However, the original characteristic data obtained by infrared thermometry cannot effectively distinguish some of the decay-like insulators from those with ageing sheaths. Therefore, it is imperative to find a new diagnostic characteristic quantity. Based on statistical data, this article first explains that existing diagnostic methods have limited diagnostic effectiveness and a high false detection rate for insulators in a slightly heated state. A full-scale temperature rise test is carried out on a batch of composite insulators returned from the field under high-humidity conditions. Two different defective insulators with similar temperature rise profiles are identified, and an electro-thermal coupling simulation model is developed based on the dielectric characteristic parameters of the above insulators for both core rod defects and sheath ageing. A new infrared diagnostic feature, the temperature rise gradient coefficient, is then obtained to identify the source of abnormal heat in insulators using statistical analysis of an infrared image gallery of abnormally hot composite insulators obtained from field inspections and laboratory tests.

Study on the Mechanism Effect of Bending Loads on the Decay-like Degradation of Composite Insulator GFRP Core Rod

“…Second, the epoxy resin matrix is defined as an isotropic elastic-plastic material. According to the Mises yield criterion, matrix damage is initiated when the maximum principal stress in a matrix element exceeds the strength limit, resulting in a stiffness reduction, as expressed in Equation (7). At this point, the matrix elements experience damage failure and are deleted.…”

“…In practical applications, composite insulators operate under diverse and challenging conditions experiencing various incidents that affect the secure and stable operation of transmission lines throughout their long-term service life. These incidents encompass flashovers under specific weather conditions, aging, and abnormal fractures of composite insulators [5][6][7][8]. Among these incidents, the anomalous fracture of composite insulators poses the most severe threat to the power system.…”