An approach to designing a connecting system is put forward for a power switching station based on local balance principle. Firstly

the electric balance of whether the demand of electricity can be met. Secondly

Aksai-dungog Railway power grid is analyzed to determine through the analysis of location connecting to the system of the power switching station

two schemes are presented. Then

the power flow and short-circuit current of small lo- cal power grid corresponding to each scheme are calculated

and the economical and technical comparison are also performed. Finally

a reasonable scheme is completely determined on the basis of local balance principle. This scheme can not only conform with the traditional principles such as on the spot balancing

saving investment

but more importandy

it considers particularly the difficulty of power transmitting outside for the west power grid of China

and can ease the pressure of power transmitting outside to some extent.