Application of static synchronous series compensators in mitigating Ferranti effect

This paper discusses a novel application of the SSSC which is a VSC-based FACTS device connected in series with the transmission line. An unloaded transmission line experiences Ferranti effect, i.e. the unloaded end of the transmission line experiences a voltage rise, which increases in magnitude as the length of the line increases. The SSSC can inject a controllable voltage in quadrature with the line current. Since the transmission line current is also in quadrature with the line voltage in the unloaded condition, the SSSC can take advantage of this to reduce the line voltage magnitude by injecting a voltage in phase with it. To verify this effect, the system is implemented in PSCAD along with a two-level VSC based SSSC with slightly altered controls. Voltage reduction at the receiving end was achieved when the SSSC was put in operation.