Small signal stability improvement of a single machine infinite bus system using SVC

FACTS (Flexible AC Transmission Systems) controllers are used to enhance power transmission capability of existing transmission corridors. Shunt FACTS controllers achieve this by improving the bus voltage profile of the system. The Static Var Compensator (SVC) is a shunt FACTS controller which is used to improve the system bus voltage profile by providing reactive power compensation. In addition, SVC firing angle modulation using a damping controller can achieve the additional objective of power oscillation damping. It is observed that SVC with only voltage controller increases the small signal stability marginally. However, when a damping controller is added, a marked increase in the system small signal stability is achieved. A damping controller can use a variety of auxiliary or supplementary signals to improve the power oscillation damping. Usually, at the SVC location, electrical power, synthesized frequency, line current etc. are used as auxiliary signals. This paper presents the small signal stability improvement of a single machine infinite bus (SMIB) system with a SVC connected at the mid-point of the transmission line. Line current signal is used as a supplementary signal for the SVC damping controller. Multiple case studies are carried out to validate the results.