Effection on Short-Circuit Current Limit of 500kV Autotransformer Neutral Grounding via Small Reactance

In this paper, with strengthening of the power grid structure recently, part of Regional Power Grid 220kV Bus single-Phase short-circuit current exceeding the three-phase short-current, First analyzed the structure of the North China Power Grid Status, power grid characteristics and the structural features of main transformer in 500kV substation, and According that making out the reasons that 220kV single-phase short-circuit current increased dramatically. According to the North China Power Grid 2009 winter big load data, selected the Anding Station, Shunyi Station, Binhai Station and Baobei Station in the North China Power Grid, used the Power System Analysis Software Package (PSASP), made main transformer neutral grounding via low resistance electrical short-circuit current calculation. According to short-circuit current calculation, analyzed the limiting effects of 500kV autotransformer neutral grounding by small reactance on 220kV single-phase short circuit current, grid structure on the low reactance limiting effects, and gived a project guidance about small reactor´s selection.