Cable Design And Self-protection Characteristics Simulation Analysis In Superconducting HVDC Transmission System

With the increasing demand for energy and the dual constraints from resources and environment,clean replacement and power replacement will be the main direction of new energy change.In order to adapt to the increasing trend of renewable energy and power consumption in terminal energy,the research of efficient,safe and environmentally friendly power transmission technology is very urgent.As one of the most promising technologies in the 21st century,the application of superconducting technology in electric power,motor,automobile,aerospace,high-energy physics and rail transportation is advancing.Among them,superconducting power application technology is the field of superconducting phenomenon that studied earlier,and also the most mature and the closest approach to large-scale application.In this paper,the design and characteristics analysis of superconducting cable in HVDC transmission system,focus on critical current,HTS DC cable design and optimization,the quench characteristics of the HTS DC cable and the current limiting characteristics of HTS DC cable in HVDC system,the main research contents are divided into the following parts:Firstly,the development history of superconducting is briefly reviewed,and the most promising superconducting materials,such as Bi-2223,YBCO,MgB₂ and iron-based superconducting materials,are mainly introduced.Including its processing technology,development level and already commercialized strip specifications and so on.According to the classification of HTS DC cable and HTS AC cable,the representative demonstration projects of HTS cable in the world are summarized.Secondly,according to critical current is the most attention problems in engineering application,combined with the characteristics of the transmission current of HTS DC cable,the theoretical calculation model of HTS strip is given.The critical current determines the transmission efficiency of the HTS DC cable,will be affected by many factors such as magnetic field,temperature and stress in the working environment.The theoretical formula of the critical current will give the functional relation between the critical current and the variables.At the same time,the concepts of AC loss,normal zone propagation velocity?NZPV?and the minimum quench energy?MQE?are introduced.Thirdly,according to the design process of HTS DC cable,the design of cable conductor,insulation design and the design of related accessories are expounded..In combination with the gap effect and polygon effect of the single and multi-layer arrangement of the HTS DC cable,the strips arrangement of the cable are optimized to reduce the cost and improve the efficiency.The Comsol Multiphysics software will be used to analyze the magnetic field distribution,critical current of HTS DC cables with different structures.Finally,the HTS DC cable can be change from superconducting state to normal state in a few milliseconds,which is very important for fast limiting of the initial shock current of the fault.Based on the quench-recovery characteristic of HTS DC cable,a superconducting cable model is established in Matlab/Simulink.When the fault occurs in DC power distribution network,LCC DC transmission and VSC DC transmission system,the influence of the current limiting function on the fault current of the system and the factors that determine the fault current suppression ability from the design of the HTS DC cable are analyzed.