Research On Terminal Stress Cone Of220kV Cold Dielectric HTS Cable

Since the discovery of HTS (high temperature superconduct) materials in1986, operation of superconducting devices in LN2temperature has become reality, rapidly speeding up the practical process of HTS materials, which soon entered the commercial stage since then. HTS cable has series advantages such as small size, light weight, large capacity, low loss, no fire hazards, and is suitable for short distance transmission of electricity and other occasions as well as urban power transmission applications. With the increase of voltage class, electrical insulating property has become the weakness that leads to frequent electrical accidents. As a result, stress cone, one of the most important cable accessories, can make better electric field distribution in terminals. The structure design, process achievement and electrical property test is surely the key techniques for development of220kV CD (cold dielectric) HTS cables.Research and development of stress cone for normal and cryogenic terminals were both discussed; PPLP and kraft paper were chosen as the additional insulation of stress cone, therefore both of their cryogenic insulation strength were obtained by carrying on breakdown experiments after wrapping samples modeled on actual HTS cables. Learning from design principles and calculation methods of normal terminal stress cone, four types stress cone with different additional insulation materials were mathematically designed, based on which the electric field distribution of the cones were simulated using finite element method and related software, and a method was proposed to optimize electric field concentration at the end of the cone. Structure of220kV terminal stress cones was determined, that is kraft paper as additional insulation, single-straight line cone, epoxy sleeve with shield ring uniforming electric field.Composition and experimental program of35kV HTS cable stress cone were put forward, and the lower cost program was determined after analyzing influences of model size on electric field. Finally, a reasonable structure design of stress cone for the220kV HTS cable terminals was proposed, where a kind of available wrapping craft for stress cone insulation was elaborated, meanwhile according to electric field distribution in cryogenic terminals the inner radius of the cryogenic terminal was initially identified.