±1100kV特高压直流输电系统换流变压器设计(英文)

Technical scheme of ±1 100 kV converter transformers is discussed in this paper.Important parameters such as impedance,capacity rating,and insulation level are introduced,and the possible design solution is discussed based on the transportation limitation,which is followed by a structure design and an integrating scheme discussion.The minimum impedance limit and natural impedance are checked considering the voltage fluctuation and the reactive power,and finally the impedance,24% for ±1 100 kV ultra high voltage direct current(UHVDC) projects,is obtained.Lightning impulse withstanding level(LIWL) and switching impulse withstanding level(SIWL) at the valve side of HY transformer is 2 300 kV and 2 100 kV respectively,about 28% and 31% higher than that of ± 800 kV projects.±1 100 kV converter transformers could be designed according to three solutions: conventional design,units in parallel,and components of transformers transported to site and assembled on site.A simple solution to integrate an UHVDC project into UHVAC systems is discussed according to the reduction of transporting transformers by railway.