Improving damping of power system oscillations using an SVC

Abstract

In today's practical power systems, the small-signal instability, mainly caused due to insufficient damping of system oscillations, has become a serious threat for the stable operation. This paper discusses the application of a Static Var Compensator (SVC), used for supporting the voltage in a system, to enhance power system small-signal stability. A power system consisting of a generating station and an infinite bus (large system) connected by a high voltage transmission line is used in this study to demonstrate the application of an SVC to improve small-signal stability. The SVC considered is installed at a sub-station at the middle of the transmission line to improve the voltage profile in the system. The EMTDC/PSCAD Transient Simulation Software is used in this study to model the system and controllers under consideration. Simulations performed under different disturbances revealed the presence of poorly damped oscillations in the system; especially, there are very poorly damped oscillations in the power flow in the transmission line. A feedback loop is incorporated to the SVC control system to improve the damping of system oscillations. The simulation results are presented to reveal the successful application of the SVC to improve small- signal stability of the power system.