Application prospect analysis for 1000 kV/220 kV UHV transformer

UHV is a promising technology for the development of grid. 1000 kV/220 kV transformer will shorten electric distance between power supplies and load, which will lead to lower cost and smaller occupation for transmission project. But it can also raise short circuit current level. Thus it is essential to analyze the prospect of 1000 kV step-down 220 kV transformer comprehensively. This paper compares the cost of direct step-down scheme by using 1000 kV/220 kV transformer and the conventional step down scheme by using 1000 kV/500 kV in series with 500 kV/220 kV transformer for the same transmission capacity. The short circuit current level of the two aforementioned schemes are also analyzed by PSASP for different gird develop stages. The requirements for using 1000 kV/220 kV transformer are finally summarized as a practice reference.