DAMPINGSUBSYNCHRONOUS OSCILLATIONS IN POWERSYSTEMSUSINGA STATICPHASE-SHIFTER

A method forsuppressingSub- synchronous Resonance(SSR) in largeturbine- generators,as a resultof seriescapacitor compensation ofpower systems,ispresented. This methodutilizesa thyristor-controlled phase-shifter tomodulatethegeneratoractive powerby injecting a quadrature phasevoltage in thesystem. Therotorspeeddeviationfrom thesynchronousspeedisusedas thecontrol signal.An eigenvalueanalysisandthecomplex torquecoefficient methodsare usedtodemon- stratethe technicalfeasibility of a static phase-shifter fordampingSSR. Theanalytical resultsareverifiedby a detaileddigital computerstudyon thefirstIEEEbenchmarkfor SSRstudies,usingtheBPA'sElectro-Magnetic TransientsProgram(EMTP).Thesimulationre- sultsindicatethatinjection of 2.4% of the systemphasevoltagein4 stepsof 0.6%,can suppressalltorsionalmodesof theFirstIEEE benchmarkmodel.