With significant increase of power cable

arc suppression coil compensation has reached its limit and

due to lag of damping cases and the control part in technology

the performance of original equipment can not meet requirements of power network. In view of operation status of the equipment

in this paper

the defects existed are analyzed and upgrading scheme is proposed. The capacity of arc suppression coil and of transformer is determined through calculation of capacitive current of system to earth and the type selection and calculation of new equipment is finished. Implementation of system assures safe operation of power system and plays an active role in improving reliable operation distribution power network.