Some aspects of power system stabilizer performance in subsynchronous resonance study

In this paper, behavioural aspects of two types of power system stabilizers (PSS), i.e., a slip-signal PSS and a Delta-P-Omega PSS are studied in a fixed series capacitor compensated system employing the IEEE first benchmark system for SSR study. The well-known slip-signal-torsional interaction is studied to understand its dependency on the magnitude of network compensation. From such a study it is noted that the slip-signal-interaction is prominent only at higher degree of line compensation. It is also shown that Delta-P-Omega PSS is immune to such torsional interactions. Further, using the eigenvalue-based study, the swing-mode damping performance of slip-signal PSS and Delta-P-Omega PSS are studied when a system is series compensated. This study not only demonstrated the superiority of Delta-P-Omega PSS, but also validated the poor performance of slip-signal PSS. All these observations are verified by carrying out simulations on PSCAD/EMTDC. To enhance the understanding about the SSR phenomenon, some fundamental observations made in the study are also listed.