In order to guarantee the safety and stability of the H-bridge cascading SSSC and to reduce the harmonics， based on the mathematical relationship between DC and AC side of the SSSC， this paper presents a formula of selecting DC capacitance with the output harmonics and fluctuation of DC voltage being taken account of. Considering the fact that the SSSC is connected to transmission line in series， the paper proposes three types of self-excitation charging schemes for the SSSC to achieve a minimal disturbance to the connected power grid. The proposed schemes are the electric bypass plus alternative charge including diode rectifier， equivalent Boost circuit and full active power PWM rectifier that gives best performance. Finally， results of EMTDC/PSCAD simulation and experiment are given in the paper.