Effect of Exciter and PSS on SSR Damping

In this paper, the effects of different types of excitation systems and PSS on the SSR damping characteristics are studied. The complex torque coefficient approach realized by time domain simulation - the test signal method is adopted. The studied system consists of a single-machine infinite bus system. Three types of excitation systems - IEEE AC1A, AC2A, ST1A excitation systems are selected as examples. Frequency scanning in the subsynchronous frequency range is performed to calculate the subsynchronous electrical damping characteristics of the unit. Effects of excitation systems with moderate or high response on the electrical damping are investigated. Two situations including excitation system without PSS and with PSS are considered. At the same time, different input signals of PSS are used respectively. In addition, the effects of the parameters of PSS on the electrical damping are also investigated. The results are analyzed in detail and some important conclusions are drawn.