Abstract—With the rapid growth of the grid structure and voltage level, some 500kV transformer substations’ 220kV side of the single-phase short-circuit current level is so large that it has a bad impact on grid stability. To solve the problems, the main reason of the growth of single-phase short-circuit current is analyzed, and the method of main transformer neutral grounding via low resistance is proposed and the mechanism of the measure is analyzed. Simulation analysis with the Power System Analysis Software Package (PSASP) shows that the method of main transformer neutral grounding via low resistance can effectively suppress the single-phase short-circuits current.

Index Terms—Single-phase short-circuit current, zero sequence impedance, autotransformer, neutral grounding.

Liu Jingyan and Liu Wenying are with the School of Electrical and Electronic Engineering, North China Electric Power University, 102206, Beijing, China (e-mail: tommy.2909@hotmail.com)
Zheng Wei is with Electric Power Research Institute of Gansu Provincial Power Company.