SMALL SIGNAL STABILITY IMPROVEMENT OF A SINGLE MACHINE INFINITE BUS SYSTEM USING A STATIC VAR COMPENSATOR

Abstract

The small signal stability of a power system is the ability of the system to maintain synchronism under small disturbances like variation in load and/or generation. The disturbances are considered sufficiently small for linearization of system equations to be permissible for the purpose of analysis. Traditional ways to improve small signal stability included power system stabilizers (PSS). Shunt FACTS Controllers like Static Var Compensator (SVC) are primarily used to improve the voltage profile and for reactive power compensation. SVC susceptance 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 observed. 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. In this work, line current signal is used as a supplementary signal, with the SVC connected at the mid-point of the transmission line. Multiple case studies with a SMIB system validate this.