Simulation of unified static VAr compensator and power systemstabilizer for arresting subsynchronous resonance

摘要

In the literature, co-ordination of static VAr compensators (SVCs)nand power system stabilizers (PSSs) using generator speed deviation ornmodal speeds as stabilizing signals is shown to damp the systemnoscillations. Though such schemes are able to damp the SSR modes fornsmall disturbances, they are unable to damp transient SSR due to largendisturbances. In this paper, improvement in the control aspect of thenSVC at the midpoint of the transmission line is suggested. This schemenattempts different auxiliary signals that include line current, computedninternal frequency and bus angle deviations. A system of configurationnsimilar to IEEE First Bench Mark model is considered, eigenvaluenanalysis has been carried out, and results indicate that bus anglendeviation signal as auxiliary control signal for SVC was able to dampnmost of the modes leaving some of them still oscillatory. The mainnfeature of the proposed work is to use combination of deviation in speednand electrical power output of the generator as input signals to PSSnwhich operates simultaneously along with SVC. Such simultaneous PSS andnSVC scheme is found to improve the damping under large disturbances i.e.nthe growth of system oscillations is arrested. The simulations arencarried out on PSCAD. The efficacy of controllers to damp SSR undernsteady-state and faulted conditions where one of the torsional modesngets excited is presented and discussed