In this paper

in view of the composite system which is converted from grid paralleling device into static synchronous series compensator（SSSC） on the basis of power transmission

the equivalent model after the transmission from the paralleling device into SSSC is set up.According to the dual compensation characteristic that SSSC can perform both capacitiveand inductive compensation

the process of regulating power flow by SSSC and the change of transmission line current before and after SSSC connected to the system are analyzed.In order to reduce the impact of short-circuit current on the system in the case of short-circuit fault

in this paper

the different short circuit fault current is limited with the feature that SSSC can be equivalently inductive impedance

thus improving the comprehensive utilization rate of the existing equipment.The equivalent model including SSSC is built in PSCAD/EMTDC.The simulation result show that SSSC can effectively adjust the power flow of line transmission and verify that SSSC has a definite current limiting function when the system has a short circuit fault.