Design Of Coid Dielectric High Temperaturc Superconducting Cable Joint

High temperature superconducting (HTS) cables are determined to be important way of future electric energy transmission, since that they have lots of advantages such as small size, light weight, low loss, without environmental pollution and so on. Cable joint is one of the most important parts in HTS cable system. And therefore the electrical and heating insulation design of the cable joint are the key technique for optimizing the cable design.Firstly, difference between structure form of HTS cable joint and that of conventional cable joint is discussed. Then further study has been carried out through a series high voltage tests on cryogenic insulating materials including certain epoxy resin, plastic polyester film and multilayer insulation paper. These tests contain power frequency withstand voltage test and lightning impulse test. Electrical characteristics of these insulating materials in LN2environment can be obtained by high voltage tests.Flowing characteristics of LN2in corrugated pipes which can be used as channels of LN2for HTS cable have been analyzed, and therefore pumping loss of HTS cable with co-flow of LN2has been obtained. Combined with hysteresis loss, eddy current loss and dielectric loss of HTS cable, we can establish longitudinal temperature distribution equation of HTS cable. Meanwhile longitudinal temperature distribution curve for3000m220kV HTS cable can be plotted.Taking35kV HTS cable joint for example, we at first calculate main parameters including winding insulation thickness, shape and length of stress cone, shape and length of counter stress cone. Then numerical analysis based on finite element method (FEM) for electrical strength of HTS cable joint was performed, which could be verification whether this model is right.Testing schemes for35kV HTS cable joint according to corresponding national standards. According to the schemes, power frequency withstand voltage test, DC withstand voltage test, lightning impulse test and partial discharge test for35kV HTS cable joint model should be carried out, of which results will finally determine whether this model is reasonable. At last, design scheme of220kV HTS cable joint is put forward, which will serve integrated experiment of220kV HTS cable system including cable body, termination and cable joint in the near future.