Design For Major Insulation Of High-voltage Cold Dielectric HTS Cable

Due to its high critical temperature more than liquid nitrogen of 77K, research on HTS application has been performed since 1986 high temperature superconductors(HTS). HTS cable, one of its application in engineering, can carry high current dendity with zero resistance, so that it has a series advantages such as small size, light weight, low loss, no fire hazards, etc., and is suitable for short distance transmission of electricity and power plants, substations and other occasions as well as large or very large urban power transmission applications. HTS cables can be divided into warm dielectric (WD) and cold dielectric (CD) in accordance with their insulation structure.The theses foceses on the main insulation design of CD HTS cable, which is one of key techniques for development of HTS cable.The insulation structure and characteristics of HTS cable conductor with different structures were discussed, simultaneously electrical properties of traditional insulating materials at room temperature are compared with those at low temperature. The electrical insulation properties of some special insulation papers, includidng withstand voltage test, partial discharge tests and dielectric loss measurement were experimentally performed. Based on electrical parameters of some insulation materials in room and 77K temperatures, we adopt Polypropylene laminated paper (PPLP) as the insulation material and main insulation layers in HTS cable.After a mini-HTS cable model with 35kV was constructed with stainless steel pipe instead of corrugated pipe, insulation tests of the model was performed to check its the insulation performance. By analysis on the differences between practical application and calculations, we suggested a more reasonable desgin and test method. According to improved test data and simulated results, a new mini-HTS cable model was designed and withstand test at power frequency alternating current (AC) of 35kV was carried out. The results indicatd that the model performances of the model meets the expected requirements, which may provide an important reference for the develoment of real-scale HTS cable. Finally, a reasonable structure design of main insulation for the 220kV HTS cable was proposed.