We extend the torque per unit velocity method for estimating the modal damping of subsynchronous oscillations to general power systems with thyristor switching devices. This allows damping of SSR by thyristor controlled series capacitors to be obtained from time domain simulations of only the electrical part of the system. Our method generalizes to the case of multiple torsional modes with the same natural frequency. A new method is used to estimate the damping and frequency of the swing mode.

more »

... orque per unit velocity methods are easier than exact eigenvalue analysis and testing on the IEEE first benchmark SSR model shows excellent agreement with exact eigenvalue analysis. Rajesh Rajaraman (S'92) received the B Tech and MS in Electrical Engineering from IIT, Bombay, India and the University of Maine-Orono and the MS in Computer Science and the P h D in Electrical Engineering from the University of Wisconsin-Madison. He is now a senior engineer at Christensen Associates, Madison WI. His interests include power system economics, subsynchronous resonance, utility power electronics and voltage collapse Ian Dobson (M'89) received the BA in mathematics from Cambridge, England in 1978 He worked for five years as a systems analyst for the British firm EASAMS Ltd, including simulation of switching circuits on contract t o Culham Laboratory, UKAEA. He received the P h D in electrical engineering from Cornel1 University in 1989 and is now associate professor of electrical engineering at the University of Wisconsin-Madison. His current interests are applications of bifurcation theory and nonlinear dynamics, voltage collapse in electric power systems and utility power electronics.