The end part of cryogenic H. V. bushing insulation design in a 230/20 kV HTS transformer

Abstract

Appealing advantages of high-temperature superconducting (HTS) transformers are very promising for the contemporary and future power delivery systems. Cryogenic insulation technology is one of the key technologies for their commercialization. In this paper insulation design of the end part of cryogenic high voltage (H. V.) bushing of a 230/20 kV HTS transformer is developed. Analytical relations and finite element method (FEM) modelling, through application of COMSOL Multiphysics software, are employed for determination of electric field distribution in this design process. Weibull 0.1% dielectric breakdown strength has been considered as criterion for insulation design. Different shape and dimension parameters have been tested for mitigation of electric field concentration. A stress cone has been employed to reduce the electric field concentration at the triple point interface of the materials. Additionally, a ring-shaped cut-outs is made on the GFRP-liquid nitrogen boundary to enhance the insulation characteristics.