This paper compares four converter topologies for the implementation of flexible ac transmission system (FACTS) controllers: three multilevel topologies (multipoint clamped (MPC), chain, and nested cell) and the well-established multipulse topology. In keeping with the need to implement very-high-power inverters, switching frequency is restricted to line frequency. The study addresses device co...

In this paper a transformerless Static Synchronous Series Compensator (SSSC) to increase the power capacity of a 230 kV transmission line is proposed. In order to eliminate the transformer, a 15-level cascade H Bridge (CHB) inverter is employed within the proposed compensator structure to inject reactive power to the transmission line. The theory of instantaneous p-q power using in the compensa...

Power systems are subjected to small–signal oscillations that can be caused by sudden change in the value of large loads. To avoid the dangers of these oscillations, the Power System Stabilizers (PSSs) are used. When the PSSs can not be effective enough, installation of the Thyristor–based compensators to increase the oscillations damping is a suitable method. In this paper, a Static Synchronou...

The characteristics of Static Synchronous Series Compensator (SSSC) based on six-pulse Voltage Source Converter (VSC), which is inserted in series into a three phase inductive system, are analyzed and calculated in detail in its inductive and capacitive operation modes, including the AC, DC current and DC capacitor voltage in one period. And the expressions for them are derived in order to asse...

in this paper a comprehensive approach is presented to improve power swings damping based on direct lyapunov method. the approach combines superconducting magnetic energy storage (smes) system with static synchronous compensator (statcom). considering the energy absorption/injection ability of smes, in transient states the combination exchanges both active and reactive powers with power system....