Research On Key Technologies Of 220kV Cold Dielectric High Temperature Superconducting Cable

High temperature superconducting(HTS)cable provides a novel possible method of electric power transmission for the future power grid due to its several advantages such as large capacity,low loss,space-saving and environment-friendly,etc.With analysis on the current status and future development trendency of HTS at home and abroad,this dissertation aims to perform the key technologies of 220kV/3kA cold dielectric(CD)HTS cable with cable conductor,jointing between two cable conductors,termination and quench detection.The specific contents are as follows:The designing structrure principles of former,conductor layer,insulation layer,shielding layer for the 220kV/3kA CD HTS cable conductor are presented.Research and calculation on various kinds of conductor losses during normal operation are carried out.Combination with the experiment,current distribution characteristics of multi-layer HTS and their effect on the cable operation losses are analyzed.Structure design of 220kV CD HTS cable is developed and analyzed by numerical simulation.The design method is used to wind a short cable model,and the current capacity under condition of rated and fault as well as retest were performed in LN2 temperature.The results show that the design is reasonable.A connecting method of copper frame between HTS cable conductors is put forward,which has the peculiarity of high strength,convenient installation and disassembly.In addition,optimal soldering length of HTS tape is obtained through the experiment.Effects of soldering temperature on the properties of polypropylene laminated paper(PPLP)are also evaluated by experiment.The insulation structure of the middle connecting device between two cable conductors is analyzed.Designed results of joint insulation part for 220kV/3kA CD HTS cable are obtained and checked by the finite element method(FEM).With analyzing the structure of the cryogenic Dewar tube used in HTS cable,a set of cryogenic Dewar corrugated pipe is designed and manufactured,and its heat leakage is evaluated through the experiment.Research of terminal devices mainly focues on structures of the current leads,stress cone and cryostat,which are simulated.With writing the software program for stress cone design,a structure design of terminal device for 220kV/3kA CD HTS cable is developed.Based on current phase difference among HTS layers of cable conductor and optical fiber temperature detecting,two kinds of effective quench detection techniques are presented,and the effectiveness is verified by both of simulating analysis and experiment.The techniques can provide two types of new quench detection method for operation of the CD HTS cables.