Damping torsional oscillations of nuclear generators by using firing delay angle modulation of HVDC schemes

Abstract The paper presents the results of hybrid simulation studies of HVDC firing delay angle (α) modulation as a countermeasure to subsynchronous resonance (SSR) torsional oscillations occurring in a nuclear generator interfaced to the rectifier terminals of an HVDC transmission scheme. SSR oscillations can be amplified owing to the negative damping introduced by the HVDC scheme. This report illustrates the α modulation scheme and presents hybrid simulator results to ascertain its effectiveness in damping the low frequency SSR oscillation due to HVDC system control interactions.