Self-startup of static series compensator

The energy-storage of the static series compensator (SSC) dictates its capability to mitigate voltage dips. Capacitors are considered the most feasible energy storage for the SSC, particularly in high power applications. However, charging techniques of such energy-storage capacitors (ESC) have not been reported in literature. This paper proposes and describes the self-charging, technique that uses the voltage source converter of the SSC to charge its ESC. The active power, used in charging, is taken at the expense of the load active power. Thus two different cases are considered. One case considers that the phase angle of the load voltage is not allowed to jump during the charging process but the magnitude of the load voltage is reduced to 95-99% of its rated value. The other case assumes that the phase angle of the load voltage is allowed to jump. In this case, the VSC of the SSC extracts active power from the grid and injects reactive power into the grid. In both cases, a proper control algorithm is presented. PSCAD/EMTDC simulation verifies the validity of the proposed technique.