DAMPING OF TORSIONAL OSCILLATIONS - A COORDINATED APPROACH

Damping of torsional oscillations using coordinated control through po wer system stabilizer (PSS) and thyristor controlled reactor(TCR) is p resented in this paper. The PSS has modal speed deviations as its feed back signal. The reactive power control is achieved through thyristor controlled reactor (TCR) at the machine terminals. Generator speed dev iation is used as auxiliary signal and terminal voltage feedback signa l as main control signal for TCR. The following control strategies hav e been analysed : a PSS with modal speed control b PSS with modal spee ds plus TCR with terminal voltage control c PSS with modal speeds plus TCR. with complete controls (voltage feed back signal and generator s peed deviation signal) The main objective of this paper is to discuss the modelling aspects and analyse different control strategies for dam ping torsional oscillations in series compensated ac transmission syst em. The control parameters like gains and time constants have been obt ained by performing repeated eigenvalue analysis. IEEE First Benchmark Model is considered for illustration.