Impact of Exciter Gain on the Transient Stability of an IEEE 9-bus System

Abstract

The voltage at the terminals of a generator is regulated using an Automatic Voltage Regulator (AVR) and thus, this is an important component of a generation plant. Fast acting exciters are used in power systems to mitigate against non-oscillatory rotor angle instability. There is also need to understand the impact of the excitation system gain on transient stability. This paper investigates transient stability of the modified IEEE 3-generator 9-Bus system with different excitation system gains. Load flow analysis is first done to ascertain the system steady state conditions. Thereafter, a three-phase fault is introduced on one of the transmission lines for 0.1 seconds and the generators’ rotor angles analyzed. For better understanding of the role of the AVR, the simulations were first run with the generators on manual excitation control and later with AVR control. The rotor angle stability was analyzed for the increased AVR exciter gain in the reference generator G1 and critical generator G2. The simulations were done using DIgSILENT PowerFactory. The results show the AVR introduces negative damping and large values of exciter gain constant lead to instability.