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Fuzzy comprehensive state evaluation of housing of silicone rubber insulators based on level difference maximization

Wang Sihua, Chen Long, Zhao Lei, Wang Junjun

Archives of Electrical Engineering

2022

Vol. 71, nr 1

57--74

The aging of composite insulators in outdoor operation for a long time has a direct impact on the safe and stable operation of the power grid. To solve this problem, fuzzy comprehensive evaluation of composite insulators based on level difference maximum is proposed. To verify the feasibility of this method, insulators in Xinjiang are sampled and the index evaluation system for composite insulators is established based on electrical, mechanical, hydrophobic and other properties, combined with operational years, geographical environment and other factors; Firstly, different membership functions are established according to index types. It is more likely to determine the grade of insulator by comparing measured data with the boundary value. Then, to solve the problem that weights cannot be effectively integrated in the combination weighting, level difference maximization is proposed (during the operation of insulators, the index which has a greater influence on the performance of insulators takes a higher proportion of the weight). Finally, on the basis of fully considering the clarity and ambiguity of grade division, the grade state of insulators is obtained by using the linear weighting method. The results show that compared with the traditional method, the improved method of the membership function and level difference maximum can realize the dynamic adjustment of the index based on the degree of information change. The method can better evaluate the insulator grade. The case study shows that the model can accurately and quickly judge the state of composite insulators, which can be used as a reference for manufacturing and maintenance departments.

Multiphysics simulation and shed structure optimization of catenary icing insulator

Wang Sihua, Wang Junjun, Zhou Lijun, Chen Long, Zhao Lei

Archives of Electrical Engineering

2021

Vol. 70, nr 3

675--688

It is not easy to make the insulators of the railway catenary for the dry and cold environment of the icy Qinghai-Tibet plateau, without causing serious ice-related flashover accidents. To study the operating status of catenary icing insulators, a two-dimensional icing model of catenary cantilever insulators was established based on the winter environmental characteristics of the Golmud station on the Qinghai-Tibet Railway. Compared different directions of ice growth, the spatial electric field distribution, and surface temperature distribution characteristics of icing insulators were analyzed by multi-physical field coupling simulation. The results show that as the thickness of the ice layer increases and the length of the icicle increases, the field intensity of the insulator gradually increases, and the surface temperature continues to rise. When the ice edge grows vertically downward, the electric field intensity of the insulator is the smallest, and the electric field intensity is the largest when the ice edge grows horizontally. Although the surface temperature of the insulator will rise with the increase of icing degree, it is lower than the freezing point and will not have a great impact on insulation performance. Secondly, when the cantilever insulator is arranged obliquely, the increase in the inclination angle will cause the electric field to increase and the temperature to rise slightly, so the inclination angle of the oblique cantilever should be reduced as much as possible during installation. Finally, the insulator with better insulation performance is obtained by optimizing the structure of the flat cantilever insulator.